Continuously variable planetary gear set

ABSTRACT

A continuously variable planetary gear set is described having a generally tubular idler, a plurality of balls distributed radially about the idler, each ball having a tiltable axis about which it rotates, a rotatable input disc positioned adjacent to the balls and in contact with each of the balls, a rotatable output disc positioned adjacent to the balls opposite the input disc and in contact with each of the balls such that each of the balls makes three-point contact with the input disc, the output disc and the idler, and a rotatable cage adapted to maintain the axial and radial position of each of the balls, wherein the axes of the balls are oriented by the axial position of the idler.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/844,821, filed on May 12, 2004, which claims priority to U.S.Provisional Application No. 60/494,376 filed Aug. 11, 2003, U.S.Provisional Application No. 60/512,600 filed Oct. 16, 2003, U.S.Provisional Application 60/537,938 filed Jan. 21, 2004 and U.S. patentapplication Ser. No. 10/788,736, filed Feb. 26, 2004, and all of theseapplications are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention relates generally to transmissions, and moreparticularly the invention relates to continuously variable planetarygear sets that can be used in transmissions as well as other industrialand land, air and water-borne vehicles.

2. Description of the Related Art

In order to provide a continuously variable transmission, varioustraction roller transmissions, in which power is transmitted throughtraction rollers supported in a housing between torque input and outputdiscs, have been developed. In such transmissions, the traction rollersare mounted on support structures which, when pivoted, cause theengagement of traction rollers with the torque discs in circles ofvarying diameters depending on the desired transmission ratio.

However, the success of these traditional solutions has been limited.For example, in one solution, a driving hub for a vehicle with avariable adjustable transmission ratio is disclosed. This method teachesthe use of two iris plates, one on each side of the traction rollers, totilt the axis of rotation of each of the rollers. However, the use ofiris plates can be very complicated due to the large number of partsthat are required to adjust the angular position of the iris platesduring shifting of the transmission. Another difficulty with thistransmission is that it has a guide ring that is configured to bepredominantly stationary in relation to each of the rollers. Since theguide ring is stationary, shifting the axis of rotation of each of thetraction rollers is difficult.

A key limitation of this design and improvements of this design is theabsence of means for generating and adequately controlling the axialforce acting as normal contact force to keep the input disc and outputdisc in sufficient frictional contact against the balls as the speedratio of the transmission changes. Due to the fact that rolling tractioncontinuously variable transmissions require various magnitudes of axialforce at various torque levels and speeds in order to prevent thedriving and driven rotating members from slipping on the speed changingfriction balls, where a constant level of axial force is applied,excessive force is applied when torque transmission levels are lower.This excessive axial force lowers efficiency and causes the transmissionto fail significantly faster than if the proper amount of force wasapplied for any particular gear ratio. The excessive force also makes itmore difficult to shift the transmission. Improvements in the field ofaxial force production have been made but further advances are required.

Further improvements have been developed for the increased performanceand efficiency of continuously variable transmissions. There is a needto incorporate these improvements into an advanced design for acontinuously variable transmission.

SUMMARY OF INVENTION

The systems and methods illustrated and described herein have severalfeatures, no single one of which is solely responsible for its desirableattributes. Without limiting the scope as expressed by the descriptionthat follows, its more prominent features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description of the Preferred Embodiments” onewill understand how the features of the system and methods provideseveral advantages over traditional systems and methods.

In a first embodiment a power-assisted steering system is described,comprising a steering wheel, an elongated steering shaft connected at afirst end to the steering wheel and connected at a second end to apinion of a rack and pinion steering assembly, a motor that providesrotational power, a plurality of balls distributed radially about thesteering shaft, each ball having a tiltable axis about which it rotates,a rotatable input disc positioned adjacent to the balls and in contactwith each of the balls, a rotatable output disc positioned adjacent tothe balls opposite the input disc and in contact with each of the balls,a rotatable idler coaxial and rotatable about the steering shaft andpositioned radially inward of and in contact with each of the balls, anda tubular output shaft positioned coaxially about the steering shaft andconnected at a first end to the output disc and connected at a secondend to the pinion. In this embodiment, the axes of the balls arecollectively responsive to an angular orientation of the steering shaftand are adapted to orient the balls in order to convert the rotationalpower of the motor to an output torque that is transmitted through theoutput disc to the output shaft in response to a change in the angularorientation of the steering shaft.

In some of these embodiments, a cage is described that is adapted tomaintain a radial and axial orientation of the balls about the idler,wherein the cage is adapted to rotate about the steering shaft. In someembodiments the input disc is fixed and does not rotate and the motor iscoupled to the cage.

An alternative embodiment is described further comprising; a planetarygear set, which comprises a sun gear rotatable about the steering shaftand coupled to the cage, a plurality of planet positioned about, engagedwith and each of which orbit the sun gear, wherein each planet gearrotates a planet shaft of its own, a ring gear that surrounds the planetgears and engages each planet gear at each planet gears furthest radialposition from the steering shaft, and a generally annular planet carrierwhich is rotatable about and coaxial with the steering shaft and whichretains and positions each of the planet shafts. In some of thesealternative embodiments, the motor is connected to the planet carrierand the planet shafts each extend from the planet carrier and terminateat a connection point with the input disc so that the planet carrierrotates the planets about the sun gear and rotates the input disc aboutthe steering shaft.

Some steering system embodiments comprise a tubular shifter having afirst end that is dynamically attached to the idler, the shifter beingangularly aligned with the steering shaft and a second end that engagesthe output shaft and is positioned axially by the output shaft such thatany rotation of the steering shaft with respect to the output shaftmoves the shifter axially, which in turn moves the idler axially, andwherein the axes of the balls are controlled by the axial position ofthe idler. Other alternative embodiments of the steering system are alsodescribed

In another embodiment, a four wheeled vehicle steering system isdescribed that comprises four variable speed wheel transmissions, eachadapted to provide torque to one wheel, wherein each of the wheeltransmissions comprising, a longitudinal axis, a plurality of ballsdistributed radially about the longitudinal axis, each ball having atiltable axis about which it rotates, a rotatable input disc positionedadjacent to the balls and in contact with each of the balls, a rotatableoutput disc positioned adjacent to the balls opposite the input disc andin contact with each of the balls, and a rotatable idler coaxial aboutthe longitudinal axis and positioned radially inward of and in contactwith each of the balls. These embodiments also comprise a plurality oftorque supplies, one for each transmission, that are adapted to providea separate input to each wheel transmission, and a control systemadapted to independently control the axial position of each of theidlers in response to a request by an operator and thereby shift atransmission ratio of each of the wheel transmissions independently suchthat the wheels of the vehicle can turn at different rates causing thevehicle to turn.

Some alternative embodiments of the four wheel steering system furthercomprise a planetary gear set mounted about the longitudinal axis ofeach of the wheel transmissions.

In yet another embodiment, a hybrid vehicle is described comprising; afirst source of rotational energy, a second source of rotational energy,and a transmission adapted to accept rotationally energy from both thefirst and second sources. In many of these embodiments the transmissioncomprises a longitudinal axis, a plurality of balls distributed radiallyabout the longitudinal axis, each ball having a tiltable axis aboutwhich it rotates, a rotatable input disc positioned adjacent to theballs and in contact with each of the balls, a rotatable output discpositioned adjacent to the balls opposite the input disc and in contactwith each of the balls, a rotatable idler coaxial about the longitudinalaxis and positioned radially inward of and in contact with each of theballs, and a rotatable cage adapted to maintain the axial and radialposition of each of the balls. In such embodiments, the first sourcesupplies rotational energy to the cage and the second energy sourcesupplies rotational energy to the input disc. In some embodiments of thehybrid vehicle, the first source of rotational energy is an internalcombustion engine and the second source of rotational energy is anelectric motor.

Some of the embodiments of the hybrid vehicle are described as furthercomprising an axial force generator adapted to generate a contact forcebetween the input disc, the output disc, the balls and the idler that isproportional to an amount of torque to be transmitted by thetransmission. The axial force generator of some embodiments comprises; abearing disc coaxial with and rotatable about the longitudinal axishaving an outer diameter and an inner diameter and having a threadedbore formed in its inner diameter, a plurality of perimeter rampsattached to a first side of the bearing disc near its outer diameter, aplurality of bearings adapted to engage the plurality of bearing discramps, a plurality of input disc perimeter ramps mounted on the inputdisc on a side opposite of the balls adapted to engage the bearings, agenerally cylindrical screw coaxial with and rotatable about thelongitudinal axis and having male threads formed along its outersurface, which male threads are adapted to engage the threaded bore ofthe bearing disc, a plurality of central screw ramps attached to an endof the screw facing the speed adjusters, and a plurality of centralinput disc ramps affixed to the input disc and adapted to engage theplurality of central screw ramps.

In still other embodiments, a variable planetary gear set is describedcomprising; a generally tubular idler, a plurality of balls distributedradially about the idler, each ball having a tiltable axis about whichit rotates, a rotatable input disc positioned adjacent to the balls andin contact with each of the balls, a rotatable output disc positionedadjacent to the balls opposite the input disc and in contact with eachof the balls such that each of the balls makes three-point contact withthe input disc, the output disc and the idler, and a rotatable cageadapted to maintain the axial and radial position of each of the balls.In such embodiments, the axes of the balls are oriented by the axialposition of the idler.

Some embodiments of the planetary gear set are describe such that thecage further comprises; an input stator support in the general shape ofa disc positioned between the balls and the input disc, an output statorsupport in the general shape of a disc positioned between the balls andthe output disc, and a plurality of spacers adapted to extend betweenand rigidly connect the input stator and output stator.

Some embodiments of the planetary gear set further comprise an axialforce generator adapted to provide a contact force between the inputdisc, the output disc, the balls and the idler that is proportional tothe amount of torque to be transferred through the gear set. In some ofthese embodiments, the axial force generator comprises a generallydisc-shaped thrust washer that is coaxial with the idler and ispositioned near the side of the input disc facing away from the ballshaving a first side facing the input disc and having a set of thrustramps formed on the first side, a set of thrust-receiving ramps formedon the input disc facing the thrust washer, and a plurality of thrustelements located between and in contact with the thrust ramps and thethrust-receiving ramps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cutaway side view of an embodiment of atransmission shifted into high.

FIG. 2 is a partial cross-sectional view of the transmission taken alongline II-II of FIG. 1.

FIG. 3 is a schematic partial cutaway side view of the idler and rampsub-assembly of the transmission of FIG. 1.

FIG. 4 is a schematic perspective view of the ball sub-assembly of thetransmission of FIG. 1.

FIG. 5 is a schematic cutaway side view of the cage sub-assembly of thetransmission of FIG. 1.

FIG. 6 is a schematic partial cutaway side view of an alternativeembodiment of the axial force generator of the transmission of FIG. 1.

FIG. 7 is a cutaway side view of the variator sub-assembly of thetransmission of FIG. 1.

FIG. 8 is a schematic cutaway side view of an alternative embodiment ofthe transmission of FIG. 1 with two variators.

FIG. 9 is a partial cross-sectional view of the transmission taken alongline IX-IX of FIG. 8.

FIG. 10 is a perspective view of the iris plate of the transmission ofFIG. 8.

FIG. 11 is a schematic cross-sectional side view of an embodiment of aninfinitely variable transmission utilizing one torque input andproviding two sources of torque output.

FIG. 12 is a schematic end-view of the embodiment of an infinitelyvariable transmission of FIG. 11.

FIG. 13 is a cross-sectional side view of an alternative embodiment of acontinuously variable transmission where the output disc is part of arotating hub.

FIG. 14 is a cross-sectional side view of an alternative embodiment of acontinuously variable transmission where the output disc is part of astationary hub.

FIG. 15 is a cross-sectional side view of another alternative axialforce generator for any of the transmission embodiments describedherein.

FIG. 16 a is a schematic side view of a power-assisted steering systemutilizing an infinitely variable transmission.

FIG. 16 b is an alternative embodiment of the steering system of FIG. 16a implementing an alternative ratio control mechanism.

FIG. 16 c is another alternative embodiment of the steering system ofFIG. 16 a implementing another alternative ratio control mechanism.

FIG. 17 is a schematic diagram of an embodiment of an infinitelyvariable transmission illustrating one possible kinematic configuration.

FIG. 18 is a schematic diagram of an embodiment of a transmission foruse in a hybrid vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the invention will now be described with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the description presented herein isnot intended to be interpreted in any limited or restrictive mannersimply because it is being utilized in conjunction with a detaileddescription of certain specific embodiments of the invention.Furthermore, embodiments of the invention may include several novelfeatures, no single one of which is solely responsible for its desirableattributes or which is essential to practicing the inventions hereindescribed.

The transmissions and drives described herein are of the type thatutilizes speed adjuster balls with axes that tilt as described in U.S.Pat. Nos. 6,241,636, 6,322,475, and 6,419,608. The embodiments describedin these patents and those described herein typically have two sidesgenerally separated by a variator portion, to be described below, aninput side and an output side. The driving side of the transmission,that is the side that receives the torque or the rotational force intothe transmission is termed the input side, and the driven side of thetransmission or the side that transfers the torque from the transmissionout of the transmission is termed the output side. As a general andabstract description of the operation of the ratio variation of many ofthe embodiments herein, an input disc and an output disc are in contactwith the speed adjuster balls. As the balls tilt on their axes, thepoint of rolling contact on one disc moves toward the pole or axis ofthe ball, where it contacts the ball at a circle of decreasing diameter,and the point of rolling contact on the other disc moves toward theequator of the ball, thus contacting the disc at a circle of increasingdiameter.

If the axis of the ball is tilted in the opposite direction, the inputand output discs respectively experience the converse relationship. Inthis manner, the ratio of rotational speed of the input disc to that ofthe output disc, or the transmission ratio, can be changed over a widerange by simply tilting the axes of the speed adjuster balls. As anarbitrary assumption for use herein, the plane connecting the centers ofthe balls will be considered to define the border between the input sideand the output side of the transmission and similar components that arelocated on both the input side of the balls and the output side of theballs are generally described herein with the same reference numbers. Asa convention often used in the following description similar componentslocated on both the input and output sides of the transmission generallyhave the suffix “a” attached at the end of the reference number if theyare located on the input side, and the components located on the outputside of the transmission generally have the suffix “b” attached at theend of their respective reference numbers.

Referring to FIGS. 1 and 2, an embodiment of a transmission 100 isillustrated having a longitudinal axis 11 about which multiple speedadjusting balls 1 are radially distributed. The speed adjusting balls 1of some embodiments stay in their annular and spatial positions aboutthe longitudinal axis 11, while in other embodiments the balls 1 arefree to orbit about the longitudinal axis 11. The balls 1 are contactedon their input side by an input disc 34 and on their output side by anoutput disc 101. The input and output discs 34, 101 are annular discsextending from an inner bore near the longitudinal axis 11 on theirrespective input and output sides of the balls 1 to a radial point atwhich they each make contact with the balls 1. The input and outputdiscs 34, 101 each have a contact surface that forms the contact areabetween each disc 34 101, and the balls 1. In general, as the input disc34 rotates about the longitudinal axis 11, each portion of the contactarea of the input disc 34 rotates about the longitudinal axis 11 andsequentially contacts each of the balls 1 during each rotation. This issimilar for the output disc 101 as well.

The input disc 34 and the output disc 101 can be shaped as simple discsor can be concave, convex, cylindrical or any other shape, depending onthe configuration of the input and output desired. In one embodiment,the input and output discs 34, 101 are spoked to make them lighter forweight sensitive applications, to allow ease of assembly by providingone or more openings wherein access is provided through the input oroutput disc 34, 101, and to allow fluid, such as lubricant and/orcoolant to flow through input and output discs 34, 101. The rollingcontact surfaces of the discs 34, 101 where they engage the speedadjuster balls 1 can have a flat, concave, convex or other shapedprofile, depending on the torque and efficiency requirements of theapplication. A concave profile where the discs 34, 101 contact the balls1 decreases the amount of axial force required to prevent slippage whilea convex profile increases efficiency. In some embodiments the contactsurface of each of the input and output discs 34, 101 is a separatereplaceable component that can be easily removed and replaced. In suchembodiments, the contact surface can be a ring made of the appropriatematerial that is threaded into the rest of the input or output disc 34,101, while in other embodiments the contact surface has a flange orother attachment surface and is attached by fasteners. The variator 401embodiment shown in FIG. 7 illustrates an input disc 34 having an inputdisc 34 that utilizes a separate and detachable disc ring 3401 attachedby such a flange assembly. The disc ring 3401 shown in this figureattaches to the input disc 34 via a flange and fastener assembly 3402consisting of a disc ring flange (not separately identified) thatextends from the outer surface of the disc ring 3401, a disc flange (notseparately identified) that extends from outer surface of the input disc34, disc ring fasteners (not separately identified) that connect thedisc ring flange to the disc flange and a locating section 3403 that canbe used by some embodiments to precisely control the position of thedisc ring 3401 with respect to the input disc 34. The locating section3403 of the illustrated embodiment is made of an outward facing edgeformed on the disc ring flange and an inward facing edge formed on theinput disc flange, the two of which cooperate to accurately control theradial and axial position of the disc ring 3401 with respect to theinput disc 34. The use of the separate contact surface, such as the discring 3401 of FIG. 7, reduces cost by allowing for replacement of thecontact surface alone while it also allows for the use of less expensivematerials for the rest of the input and output discs 34, 101.

Additionally, the balls 1 all contact an idler 18 on their respectiveradially innermost point. The idler 18 is a generally cylindricalcomponent that rests coaxially about the longitudinal axis 11 andassists in maintaining the radial position of the balls 1. Withreference to the longitudinal axis 11 of many embodiments of thetransmission, the contact surfaces of the input disc 34 and the outputdisc 101 can be located generally radially outward from the rotationalaxes of the balls 1, with the idler 18 located radially inward from theballs 1, so that each ball 1 makes three-point contact with the idler18, the input disc 34, and the output disc 101. The input disc 34, theoutput disc 101, and the idler 18 can all rotate about the samelongitudinal axis 11 in many embodiments, and are described in fullerdetail below. The contact surfaces of the input disc 34, the output disc101 and the balls 1 can be made of, or treated with, any knowncompositions or can undergo any known material treatment to promoteadvantageous material performance characteristics of these components.Such materials and treatments are described more completely below.

FIG. 1 illustrates an embodiment of a continuously variable transmission100 that is shrouded in a case 40 which protects the transmission 100,contains lubricant, aligns components of the transmission 100, andabsorbs forces of the transmission 100. A case cap 67 can, in certainembodiments, cover the open end of the input side of the case 40, whichopening allows for assembly of the internal components of thetransmission 100. The case cap 67 is generally shaped as a disc with abore through its center, which allows for passage therethrough of aninput shaft 69 as described further below, and that has a set ofexternal threads at its outer diameter that thread into a correspondingset of internal threads on the inner diameter of the case 40. Althoughin other embodiments, the case cap 67 can be fastened to the case 40using matching flanges or it can be held in place by a snap ring and acorresponding groove in the case 40, and would therefore not need to bethreaded at its outer diameter. In embodiments utilizing fasteners toattach the case cap 67, the case cap 67 extends to the diameter of thecase 40 so that case fasteners (not shown) used to bolt the case 40 tothe machinery to which the transmission 100 is attached can be passedthrough corresponding holes in the case cap 67.

The case cap 67 of the embodiment illustrated in FIG. 1 has acylindrical portion extending from an area near its outer diametertoward the output side of the transmission 100 for additional support ofother components of the transmission 100. At the heart of theillustrated transmission 100 embodiment is a plurality of balls 1 thatare typically spherical in shape and are radially distributedsubstantially evenly or symmetrically about the centerline, orlongitudinal axis 11 of rotation of the transmission 100. In theillustrated embodiment, eight balls 1 are used. However, it should benoted that more or fewer balls 1 could be used depending on the use ofthe transmission 100. For example, the transmission may include 3, 4, 5,6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more balls 1. The provision formore than 3, 4, or 5 balls 1 can more widely distribute the forcesexerted on the individual balls 1 and their points of contact with othercomponents of the transmission 100 and can also reduce the forcenecessary to prevent the transmission 100 from slipping at the ball 1contact patches. Certain embodiments in applications with low torque buta high transmission ratio uses few balls 1 of relatively largerdiameters, while certain embodiments in applications with high torqueand a high transmission ratio can use more balls 1 or relatively largerdiameters. Other embodiments, in applications with high torque and a lowtransmission ratio and where high efficiency is not important, use moreballs 1 of relatively smaller diameters. Finally, certain embodiments,in applications with low torque and where high efficiency is notimportant, use few balls 1 of relatively smaller diameters.

Ball axles 3 are inserted through holes that run through the center ofeach of the balls 1 to define an axis of rotation for each of the balls1. The ball axles 3 are generally elongated shafts over which the balls1 rotate, and have two ends that extend out of either side of the holethrough the balls 1. Certain embodiments have cylindrically shaped ballaxles 3, although any shape can be used. The balls 1 are mounted tofreely rotate about the ball axles 3.

In certain embodiments, bearings (not separately illustrated) areutilized to reduce the friction between the outer surface of the ballaxles 3 and the surface of the bore through the corresponding ball 1.These bearings can be any type of bearings situated anywhere along thecontacting surfaces of the balls 1 and their corresponding ball axles 3,and many embodiments will maximize the life and utility of such bearingsthrough standard mechanical principles common in the design of dynamicmechanical systems. In some such embodiments, radial bearings arelocated at each end of the bore through the balls 1. These bearings canincorporate the inner surface of the bore or the outer surface of theball axles 3 as their races, or the bearings can include separate racesthat fit in appropriate cavities formed in the bore of each ball 1 andon each ball axle 3. In one embodiment, a cavity (not shown) for abearing is formed by expanding the bore through each ball 1 at least atboth ends an appropriate diameter such that a radial bearing, roller,ball or other type, can be fitted into and held within the cavity thusformed. In another embodiment, the ball axles 3 are coated with afriction reducing material such as babbit, Teflon or other suchmaterial. In yet other embodiments, combination bearing races are formedat each exit of the bore through each ball 1 and a correspondingcombination bearing race is formed at locations on the ball axles 3 thatcorrespond to the respective races of the ball 1. The combinationbearings utilized in such embodiments can be any type of combinationbearings and including the types described below.

Many embodiments also minimize the friction between the ball axles 3 andthe balls 1 by introducing lubrication in the bore of the ball axles 3.The lubrication can be injected into the bore around the ball axles 3 bya pressure source, or it can be drawn into the bore by forming riflingor helical grooves on the ball axles 3 themselves. Further discussion ofthe lubrication of the ball axles 3 is provided below.

In FIG. 1, the respective axes of rotation of each of the balls 1 areshown tilted in a direction that puts the transmission in a high ratio,wherein the output speed is greater than the input speed. If the ballaxles 3 are horizontal, that is parallel to the longitudinal axis 11 ofthe transmission 100, the transmission 100 is in a 1:1 input rotationrate to output rotation rate ratio, wherein the input and outputrotation speeds are equal.

FIGS. 1, 3, and 4 illustrate how the axes of the balls 1 can be tiltedin operation to shift the transmission 100. Referring to FIGS. 3 and 4,a plurality of legs 2, which in many embodiments are generally struts,are attached to the ball axles 3 near each of the ends of the ball axles3 that extend beyond the ends of the holes bored through the balls 1.Each leg 2 extends from its point of attachment to its respective ballaxle 3 radially inward toward the longitudinal axis 11 of thetransmission 100. In one embodiment, each of the legs 2 has athrough-bore that receives a respective end of one of the ball axles 3.The ball axles 3 preferably extend through the legs 2 such that theyhave an end exposed beyond each leg 2. In the illustrated embodiments,the ball axles 3 advantageously have rollers 4 coaxially and slidinglypositioned over the exposed ends of the ball axles 3. The rollers 4 aregenerally cylindrical wheels fitted over the ball axles 3 outside of andbeyond the legs 2 and rotate freely about the ball axles 3. The rollers4 can be attached to the ball axles 3 via spring clips or other suchmechanism, or they can ride freely over the ball axles 3. The rollers 4can be radial bearings for instance, where the outer races of thebearings form the wheel or rolling surface. Each of the rollers 4 ofsome embodiments fit over a roller shaft (not separately shown) that isseparate from the ball axles 3 and is attached to the leg 2 at aradially inward position as illustrated in FIG. 15, which allows theinput and output discs 34, 101 to have a smaller diameter. Asillustrated in FIGS. 1 and 5, the rollers 4 and the ends of the ballaxles 3 fit inside grooves 86 formed by or in a pair of stators 80 a, 80b.

The input and output stators 80 a, 80 b of the embodiment illustrated inFIGS. 1 and 5 are generally in the form of parallel discs annularlylocated about the longitudinal axis 11 of the transmission on eitherside of the balls 1. The stators 80 a, 80 b of many embodiments arecomprised of stator discs 81 and stator curves 82. The input stator disc81 a and output stator disc 81 b, respectively, are generally annulardiscs of substantially uniform thickness with multiple apertures to bediscussed further below. Each input and output stator disc 81 a, 81 bhas a first side 88 that faces the balls 1 and a second side (notseparately shown) that faces away from the balls 1. Multiple statorcurves 82 are attached to the first side of the stator discs 81 a, 81 b.The stator curves 82 are curved surfaces attached or affixed to thestator discs 81 a, 81 b that each has a concave face 90 facing towardthe balls 1 and a convex face 91 facing away from the balls 1 andcontacting their respective stator discs 81. In some embodiments, thestator curves 82 are integral with or formed on the stator discs 81 a,81 b. The stator curves 82 of many embodiments have a substantiallyuniform thickness and have at least one aperture (not separately shown)used to align and attach the stator curves 82 to each other and to thestator discs 81. The stator curves 82 of many embodiments, or the statordiscs 81 a, 81 b where integral parts are used, include a slot 710 thataccepts a flat spacer 83, which allows further positioning and alignmentof the stator curves 82 and stator discs 81 a, 81 b. The flat spacers 83are generally flat and generally rectangular pieces of rigid materialthat extend between and interconnect the input stator 80 a and theoutput stator 80 b. The flat spacers 83 fit within the slots 710 formedin the stator curves 82. In the illustrated embodiment, the flat spacers83 are not fastened or otherwise connected to the stator curves 82;however, in some embodiments the flat spacers 83 are attached to thestator curves 82 by welding, adhesive, or fastening.

Also illustrated in FIG. 5, multiple cylindrical spacers 84, of agenerally cylindrical shape with bores at least in each end, areradially positioned inside of the flat spacers 83 and also connect andposition the stator discs 81 and stator curves 82. The bores of thecylindrical spacers 84 accept one spacer fastener 85 at each end. Thespacer fasteners 85 are designed to clamp and hold the stator discs 81a, 81 b, the stator curves 82, the flat spacers 83, and the cylindricalspacers 84 together, which collectively form a cage 89. The cage 89maintains the radial and angular positions of the balls 1 and aligns theballs 1 with respect to one another.

Still referring to FIGS. 1, 4 and 5, the rotational axes of the balls 1are changed by moving either the input-side or output-side legs 2radially out from the axis of the transmission 100, which tilts the ballaxles 3. As this occurs, each roller 4 fits into and follows a groove86, which is slightly larger than the diameter of the roller 4, and isformed by the space between each pair of adjacent stator curves 82. Therollers 4 therefore roll along the surface of the sides 92, 93 of thestator curves 82, a first side 92 and a second side 93 for each statorcurve 82, in order to maintain the plane of movement of the ball axles 3in line with the longitudinal axis 11 of the transmission 100. In manyembodiments, each roller 4 rolls on a first side 92 of the stator curve82 on the input side of the transmission 100 and on the correspondingfirst side 92 of the corresponding output stator curve 82. The rollers 4are slightly smaller in diameter than the width of the grooves 86 formedbetween the stator curves 82, forming a small gap between the edges ofthe grooves 86 and the circumference of each corresponding roller.

Still referring to FIGS. 1, 4 and 5, if the opposing sets of statorcurves 82 on the input stator 80 a and output stator 80 b were inperfect alignment, in some embodiments the small gap between thecircumferences of the rollers 4 and the grooves 86 would allow the ballaxles to slightly tilt and become misaligned with the longitudinal axis11 of the transmission 100. This condition produces sideslip, asituation where the balls axles 3 are allowed to slightly movelaterally, which lowers overall transmission efficiency. In someembodiments, the stator curves 82 on the input and output sides of thetransmission 100 may be slightly offset from each other so that the ballaxles 3 remain parallel with the axis of the transmission 100. Anytangential force, mainly a transaxial force, the balls 1 may apply tothe ball axles 3 is absorbed by the ball axles 3, the rollers 4 and thefirst sides 92, 93 of the stator curves 82. As the transmission 100 isshifted to a lower or higher transmission ratio by changing therotational axes of the balls 1, each one of the pairs of rollers 4,located on the opposite ends of a single ball axle 3, move in oppositedirections along their respective corresponding grooves 86 by rolling upor down a respective side of the groove 86.

Referring to FIGS. 1 and 5, the cage 89 can be rigidly attached to thecase 40 with one or more case connectors 160. The case connectors 160extend generally perpendicularly from the radial outermost part of theflat spacers 83. The case connectors 160 can be fastened to the flatspacers 83 or can be formed integrally with the flat spacers 83. Theoutside diameter formed roughly by the outsides of the case connectors160 is substantially the same dimension as the inside diameter of thecase 40 and holes in both the case 40 and case connectors 160 providefor the use of standard or specialty fasteners, which rigidly attach thecase connectors 160 to the case 40, thus bracing and preventing the cage40 from moving. The case 40 has mounting holes for attaching the case 40to a frame or other structural body. In other embodiments, the caseconnectors 160 can be formed as part of the case 40 and provide alocation for attachment of the flat spacers 83 or other cage 89component in order to immobilize the cage 89.

FIGS. 1, 4, and 5 illustrate an embodiment including a pair of statorwheels 30 attached to each of the legs 2 that roll on the concave face90 of the curved surfaces 82 along a path near the edge of the sides 92,93. The stator wheels 30 are attached to the legs 2 generally in thearea where the ball axles 3 pass through the legs 2. The stator wheels30 can be attached to the legs 2 with stator wheel pins 31, which passthrough a bore through the legs 2 that is generally perpendicular to theball axles 3, or by any other attachment method. The stator wheels 30are coaxially and slidingly mounted over the stator wheel pins 31 andsecured with any type of standard fasteners, such as snap rings forexample. In some embodiments, the stator wheels 30 are radial bearingswith the inner race mounted to the stator wheel pins 31 and the outerrace forming the rolling surface. In certain embodiments, one statorwheel 30 is positioned on each side of a leg 2 with enough clearancefrom the leg 2 to allow the stator wheels 30 to roll radially along theconcave faces 90, with respect to the longitudinal axis 11 of thetransmission 100, when the transmission 100 is shifted. In certainembodiments, the concave faces 90 are shaped such that they areconcentric about a radius from the longitudinal axis 11 of thetransmission 100 formed by the center of the balls 1.

Still referring to FIGS. 1, 4, and 5, guide wheels 21 are illustratedthat can be attached to the end of the legs 2 that are nearest thelongitudinal axis 11 of the transmission 100. In the illustratedembodiment, the guide wheels 21 are inserted into a slot formed in theend of the legs 2. The guide wheels 21 are held in place in the slots ofthe legs 21 with guide wheel pins 22, or by any other attachment method.The guide wheels 21 are coaxially and slidingly mounted over the guidewheel pins 22, which are inserted into bores formed in the legs 2 oneach side of the guide wheels 21 and perpendicular to the plane of theslot. In some embodiments, the legs 2 are designed to elasticallydeflect relatively slightly in order to allow for manufacturingtolerances of the parts of the transmission 100. The ball 1, the legs 2,the ball axle 3, the rollers 4, the stator wheels 30, the stator wheelpins 31, the guide wheels 21, and the guide wheel pins 22 collectivelyform the ball/leg assembly 403 seen in FIG. 4.

Referring to the embodiment illustrated in FIGS. 1, 3, and 5, shiftingis actuated by controlling the tension applied to a flexible input cable155 a and a flexible output cable 155 b. Both the input cable 155 a andthe output cable 155 b extend through holes in the case 40 and thenthrough the first end of an input flexible cable housing 151 a and anoutput flexible cable housing 151 b. The input flexible cable housing151 a and the output flexible cable housing 151 b of the illustratedembodiment are flexible elongated tubes that guide the input cable 155 aand output cable 155 b radially inward toward the longitudinal axis 11then longitudinally out through holes in the stator discs 81 a, b andthen again radially inward where the second end of the input and outputflexible cable housings 151 a, b are inserted into and attach to thefirst end of input and output rigid cable housings 153 a, b,respectively. The input and output rigid cable housings 153 a, b, of theillustrated embodiment are inflexible tubes through which the cables 155a, b, pass and are guided radially inward from the second ends of theflexible cable housings 151 a, b and then direct the cables 155 a, blongitudinally through holes in the stator discs 81 a, b and toward asecond end of the rigid cable housings 153 a, b near the idler 18. Inmany embodiments, the cables 155 a, b are attached at their second endsto an input shift guide 13 a, and an output shift guide 13 b (describedfurther below) with conventional cable fasteners, or other suitableattachment means. As will be discussed further below, the shift guides13 a, 13 b position the idler 18 axially along the longitudinal axis 11and position the legs 3 radially, thereby changing the axes of the balls1 and the ratio of the transmission 100.

When output cable 155 b applies a tension force to the output shiftguide 13 b, input cable 155 a gives way and allows the idler 18 to moveaxially toward the output side of the transmission 100 thereby shiftingthe transmission 100 toward low. When input cable 155 a applies atension force to the input shift guide 13 a, output cable 155 b givesway and allows the idler 18 to move axially toward the input side of thetransmission 100 thereby shifting the transmission 100 toward high.

Referring now to FIGS. 3, 4 and 5, the illustrated shift guides 13 a, b,are each generally of the form of an annular ring with inside andoutside diameters, and are shaped so as to have two sides. The firstside is a generally straight surface that dynamically contacts andaxially supports the idler 18 via two sets of idler bearings 17 a, 17 b,which are each associated with a respective shift guide 13 a, b. Thesecond side of each shift guide 13 a, b, the side facing away from theidler 18, is a cam side that can have a straight or flat radial surface14 towards the inner diameter of the shift guides 13 a, b, whichtransitions to a convex curve 97 towards the outer diameter of the shiftguides 13 a, b. At the inner diameter of the first side of the shiftguides 13 a, b a longitudinal tubular sleeve 417 a, b extends axiallytoward the opposing shift guide 13 a, b in order to mate with thetubular sleeve 417 a, b from that shift guide 13 a, b. In someembodiments the shift guides 13 a, b, have a convex curve 97 on theirrespective first sides from their inside diameter to their outsidediameter. In some embodiments, as illustrated in FIG. 3, the tubularsleeve of the input side shift guide 13 a has part of its inner diameterbored out to accept the tubular sleeve of the output shift guide 13 b.Correspondingly, a portion of the outer diameter of the tubular sleeveof the output shift guide 13 b has been removed to allow a portion ofthat tubular sleeve 417 a, b to be inserted into the tubular sleeve 417a, b of the input shift guide 13 a. This provides additional stabilityto the shift guides 13 a, b of such embodiments.

The cross-section side view of the shift guides 13 a, b illustrated inFIG. 3 shows that, in this embodiment, the flat surface 14 profile ofthe side facing away from the idler 18 is perpendicular to thelongitudinal axis 11 up to a radial point where the guide wheels 21contact the shift guides 13 a, b, if the ball axles 3 are parallel withthe longitudinal axis 11 of the transmission 100. From this point movingout toward the perimeter of the shift guides 13 a, b, the profile ofeach of the shift guides 13 a, b curves in a convex shape. In someembodiments, the convex curve 97 of a shift guide 13 a, b can be aradius or composed of multiple radii, or is shaped hyperbolically,asymptotically or otherwise in any other curved or curvilinear shape. Asthe transmission 100 is shifted toward low, the input guide wheels 21 aroll toward the longitudinal axis 11 on the flat 14 portion of shiftguide 13 a, and the output guide wheels 21 b roll on the convex curved97 portion of the shift guide 13 b away from the longitudinal axis 11.The shift guides 13 a, b, can be attached to each other by eitherthreading the tubular sleeve of the input shift guide 13 a with malethreads and the tubular sleeve of the output sleeve 13 b with femalethreads, or vice versa, and threading the shift guides 13 a, b,together. One shift guide 13 a, b, either the input or output, can alsobe pressed into the other shift guide 13 a, b. The shift guides 13 a, bcan also be attached by other methods such as glue, metal adhesive,welding or any other means.

The convex curves 97 of the two shift guides 13 a, b, act as camsurfaces, each contacting and pushing the multiple guide wheels 21. Theflat surface 14 and convex curve 97 of each shift guide 13 a, b contactsthe associated guide wheels 21 so that as the shift guides 13 a, b, moveaxially along the longitudinal axis 11, the guide wheels 21 ride alongthe shift guide 13 a, b surface 14, 97 in a generally radial directionforcing the leg 2 radially out from, or in toward, the longitudinal axis11, thereby changing the angle of the ball axle 3 and the rotationalaxis of the associated ball 1.

Referring to FIGS. 3 and 5, the idler 18 of some embodiments is locatedin a trough formed between the first sides and the sleeve portions ofthe shift guides 13 a, b, and thus moves in unison with the shift guides13 a, b. In certain embodiments, the idler 18 is generally tubular andof one outside diameter and has two sides, one near the input stator 80a, and one near the output stator 80 b. In other embodiments, the outerdiameter and inside diameters of the idler 18 can be non-uniform and canvary or be any shape, such as ramped or curved. The idler 18 has aninput and output idler bearing 17 a, b, on each end of its insidediameter. The idler bearings 17 a, 17 b provide rolling contact betweenthe idler 18 and the shift guides 13 a, b. The idler bearings 17 a, 17 bare located coaxially around the sleeve portion of the shift guides 13a, b at or near the junction of the radial extensions and the tubularsleeve of each shift guide 13 a, b, allowing the idler 18 to freelyrotate about the axis of the transmission 100. The idler bearings 17 a,b can be any type of radial or combination radial-thrust bearing andmany of the variations described below can be utilized.

A sleeve 19 is fit around the longitudinal axis 11 of the transmission100 inside the inside diameter of both of the shift guides 13 a, b. Thesleeve 19 is a generally tubular component that is held in operablecontact with an inside bearing race surface of each of the shift guides13 a, b by an input sleeve bearing 172 a and an output sleeve bearing172 b. The sleeve bearings 172 a, b, provide for rotation of the sleeve19 by rolling along an outer bearing race complimentary to the races ofthe shift guides 13 a, b and can be any of the types of bearingsdisclosed herein or known in the art. The idler 18, the idler bearings17 a, 17 b, the sleeve 19, the shift guides 13 a, 13 b, and the sleevebearings 172 a, 172 b collectively form the idler assembly 402, seen inFIG. 3.

Referring to FIGS. 1, 2, and 3, the sleeve 19 of some embodiments hasits inside diameter threaded to engage an idler rod 171 that is threadedinto the sleeve 19. The idler rod 171 of the illustrated embodiment is agenerally cylindrical rod that lies along the longitudinal axis 11 ofthe transmission 100. In some embodiments, the idler rod 171 is threadedat least partially along its length to allow threaded engagement withthe sleeve 19. The first end of the idler rod 171, which faces theoutput side of the transmission 100, is preferably threaded through thesleeve 19 and extends out past the output side of the sleeve 19 where itextends into or beyond the inside diameter of the output disc 101. Insuch embodiments, the idler rod 171 is axially positioned by the sleeve19, and therefore the idler 18, through the threaded engagement. Inother embodiments, the idler rod 171 can be moved axially by a controlmechanism (not shown) to position the sleeve 19 and the idler 18 inorder to control the transmission ratio of the transmission 100. Someexamples of such control mechanisms are disclosed below, although anyaxial positioning control mechanism known in the art can be used toposition the idler rod 171 and thereby control the transmission ratio.

Referring to FIGS. 3 and 5, the limits of the axial movement of theshift guides 13 a, b define the shifting range of the transmission 100.In some embodiments, axial movement of the shift guides 13 a, b islimited by inside faces 88 a, b, on the stator discs 81 a, b, which theshift guides 13 a, b contact. In some of these embodiments, at anextreme high transmission ratio, the input-side shift guide 13 acontacts the inside face 88 a on the input stator disc 81 a, and at anextreme low transmission ratio, the output-side shift guide 13 bcontacts the inside face 88 on the output stator disc 81 b. In manyembodiments, the curvature of the convex curves 97 of the shift guides13 a, b, is functionally dependent on the distance from the center of aball 1 to the center of the guide wheel 21, the radius of the guidewheel 21, the angle between lines formed between the two guide wheels 21and the center of the ball 1, and the angle of tilt of the ball 1 axis.

Referring to FIGS. 1 and 5, a spoked input disc 34 utilized in someembodiments instead of a solid disc, located adjacent to the stator 80a, partially encapsulates but generally does not contact the stator 80a. The input disc 34 may have two or more spokes or may be a solid disc.The spokes in such embodiments reduce weight and aid in assembly of thetransmission 100. In other embodiments a solid disc can be used. Theinput disc 34 has two sides, a first side that contacts with the balls1, and a second side that faces opposite the first side. The input disc34 is generally an annular disk that fits coaxially over, and extendsradially from, a set of female threads or nut 37 at an inner diameter.As mentioned above, the input disc 34 is in rotating contact with theballs 1 along a circumferential ramped or bearing contact surface on alip of the first side of the input disc 34, the side facing the balls 1.As also mentioned above, some embodiments of the input disc 34 have aset of female threads 37, or a nut 37, inserted into its insidediameter, and the nut 37 is threaded over a screw 35, thereby engagingthe input disc 34 with the screw 35.

Referring to FIGS. 1 and 3, the screw 35 is attached to and rotated by adrive shaft 69. The drive shaft 69 is generally cylindrical and in someembodiments has an inner bore, a first end facing towards the outputside, a second end facing toward the input side, and a generallyconstant outer diameter. At the first end, the drive shaft 69 is rigidlyattached to and rotated by the torque-input device, usually a gear, asprocket, or a crankshaft from a motor. The drive shaft 69 has axialsplines 109 extending from its second end to engage and rotate acorresponding set of splines (not separately identified) formed on theinside diameter of the screw 35. A set of central drive shaft ramps 99,which, on a first side facing the output side of the transmission 100,is generally a set of raised inclined surfaces on an annular disc thatis positioned coaxially over the drive shaft 69, has mating prongs thatmate with the splines 109 on the drive shaft 99, are rotated by thedrive shaft 69, and are capable of moving axially along the drive shaft69.

Still referring to FIGS. 1 and 3, a pin ring 195 contacts a second sideof the central drive shaft ramps 99, which faces the input side of thetransmission 100. The pin ring 195 is a rigid ring that is coaxiallypositioned over the idler rod 171, is capable of axial movement and hasa transverse bore that holds an idler pin 196 in transverse alignmentwith the idler rod 171. The idler pin 196 is an elongated rigid rod thatis slightly longer than the diameter of the pin ring 195 and which isinserted through an elongated slot 173 in the idler rod 171 and extendsslightly beyond the pin ring 195 at both its first and second ends whenit is inserted into the bore of the pin ring 195. The elongated slot 173in the idler rod 171 allows for axial movement of the idler rod 171 tothe right, as illustrated in FIG. 1, without contacting the pin 196 whenthe transmission 100 is shifted from 1:1 toward high. However, when thetransmission 100 is shifted from 1:1 toward low, the side on the inputend of the elongated slot 173 contacts the pin 196, which then operablycontacts the central drive shaft ramps 99 via the pin ring 195. Theidler rod 171 is thus operably connected to the central drive shaftramps 99 when the transmission is between 1:1 and low so that when theidler rod 171 moves axially the central drive shaft ramps 99 also moveaxially in conjunction with the idler rod 171. The ramp surfaces of thecentral drive shaft ramps 99 can be helical, curved, linear, or anyother shape, and are in operable contact with a set of correspondingcentral bearing disc ramps 98. The central bearing disc ramps 98 haveramp faces that are complimentary to and oppose the central drive shaftramps 99. On a first side, facing the output side of the transmission100, the central bearing disc ramps 98 face the central drive shaftramps 99 and are contacted and driven by the central drive shaft ramps99.

The central bearing disc ramps 98 are rigidly attached to a bearing disc60, a generally annular disc positioned to rotate coaxially about thelongitudinal axis 11 of the transmission 100. The bearing disc 60 has abearing race, positioned near its perimeter on its side that faces awayfrom the balls 1, which contacts a bearing disc bearing 66. The bearingdisc bearing 66 is an annular thrust bearing at the perimeter of thebearing disc 60 and is positioned between the bearing disc 60 and theinput disc 34. The bearing disc bearing 66 provides axial and radialsupport for the bearing disc 60 and in turn is supported by a bearingrace on a case cap 67, which acts with the case 40 to partiallyencapsulate the inner parts of the transmission 100. In someembodiments, the bearing disc bearing 66 is a combination radial thrustbearing and can be any type of such bearing, such as those describedbelow.

Referring to FIG. 1, the case cap 67 described above has a tubularportion extending toward the output end from at or near its perimeterand also having a bore through its center. The case cap 67, in additionto the functions described above, absorbs axial and radial forcesproduced by the transmission 100, and seals the transmission 100,thereby preventing lubricant from escaping and contamination fromentering. As was mentioned above, the case cap 67 has a bearing racethat contacts the bearing disc bearing 66 near the perimeter of thebearing disc 60 that is located at the inside of the output end of thetubular extension from the case cap 67. The case cap 67 also has asecond bearing race facing the output side located near the insidediameter of its annular portion that mates with a drive shaft bearing104. The drive shaft bearing 104 can be a combination thrust and radialbearing that provides axial and radial support to the drive shaft 69,and can be any type of suitable bearing known in the art or describedherein. The drive shaft 67 has a bearing race formed on its outsidediameter facing the input side that mates with the drive shaft bearing104, which transfers the axial force produced by the screw 35 to thecase cap 67. An input bearing 105, adds support to the drive shaft 69and is coaxially positioned over the drive shaft 69 and mates with athird race on the input side of the inside diameter of the case cap 67opposite the drive shaft bearing 104. A cone nut 106, which is agenerally cylindrical threaded nut with a bearing race designed toprovide a running surface for the input bearing 105, is threaded overthe drive shaft 69 and supports the input bearing 105.

Referring to the embodiment illustrated in FIG. 1, a set of multipleperimeter ramps 61, generally forming a ring about the longitudinal axis11, is rigidly attached to the bearing disc 60. The perimeter ramps 61are multiple annular inclined surfaces that are positioned radiallyabout the longitudinal axis 11 and are positioned against or formed onthe bearing disc 60 and face the output side of the transmission 100.The inclined surfaces can be curved, helical, linear, or another shapeand each one creates a wedge that produces an axial force that isapplied to a corresponding one of multiple ramp bearings 62. The rampbearings 62 are spherical but can be cylindrical, conical, or anothergeometric shape, and are housed in a bearing cage 63. The bearing cage63 of the illustrated embodiment is generally ring shaped with multipleapertures that contain the individual ramp bearings 62. A set of inputdisc ramps 64 is rigidly attached to, or formed as part of, the inputdisc 34. The input disc ramps 64 in some embodiments are complimentaryto and face the perimeter ramps 61. In some embodiments, the input discramps 64 are also in the form of a bearing race that aligns and assistin centering the ramp bearings 62 radially relative to the longitudinalaxis 11. The ramp bearings 62 respond to variations in torque by rollingup or down the inclined faces of the perimeter ramps 61 and the inputdisc ramps 64.

Referring now to FIGS. 1 and 3, an axial force generator 160 is made upof various components that create an axial force that is generated andis applied to the input disc 34 to increase the normal contact forcebetween the input disc 34 and the balls 1, which is a component in thefriction the input disc 34 utilizes in rotating the balls 1. Thetransmission 100 produces sufficient axial force so that the input disc34, the balls 1, and the output disc 101 do not slip, or slip only anacceptable amount, at their contact points. As the magnitude of torqueapplied to the transmission 100 increases, an appropriate amount ofadditional axial force is required to prevent slippage. Furthermore,more axial force is required to prevent slippage in low than in high orat a 1:1 speed ratio. However, providing too much force in high or at1:1 can, in many instances, shorten the lifespan of the transmission100, reduce efficiency, and/or necessitate larger components to absorbthe increased axial forces. In some embodiments, the axial forcegenerator 160 will vary the axial force applied to the balls 1 as thetransmission 100 is shifted and also as torque is varied. In someembodiments, the transmission 100 accomplishes both these goals. Thescrew 35 is designed and configured to provide an axial force that isseparate and distinct from that produced by the perimeter ramps 61. Insome embodiments, the screw 35 produces less axial force than theperimeter ramps 61, although in other versions of the transmission 100,the screw 35 is configured to produce more force than the perimeterramps 61. Upon an increase in torque, the screw 35 rotates slightlyfarther into the nut 37 to increase axial force by an amountproportional to the increase in torque. If the transmission 100 is in a1:1 ratio and the user or vehicle shifts into a lower speed, the idlerrod 171, moves axially toward the input side, along with the sleeve 19,sleeve bearings 172, shift guides 13 a, b, and idler 18. The idler rod171 contacts the central drive shaft ramps 99 through the pin 196 andpin ring 195, causing the central drive shaft ramps 99 to move axiallytoward the output side. The ramped surfaces of the central drive shaftramps 99 contact the opposing ramped surfaces of the central bearingdisc ramps 98, causing the central bearing disc ramps 98 to rotate thebearing disc 67 and engage the perimeter ramps 61 with the ramp bearings62 and the input disc ramps 64. The central drive shaft ramps 99 and thecentral bearing disc ramps 98 perform a torque splitting function,shifting some of the torque from the screw 35 to the perimeter ramps 61.This increases the percentage of transmitted torque that is directedthrough the perimeter ramps 61, and due to the fact the perimeter ramps61 are torque sensitive as described above, the amount of axial forcethat is generated increases.

Still referring to FIGS. 1 and 3, when shifting into low, the idler 18moves axially towards the output side, and is pulled toward low by areaction of forces in the contact patch. The farther the idler 18 movestoward low, the stronger it is pulled. This “idler pull,” whichincreases with an increase in normal force across the contact as well asshift angle, also occurs when shifting into high. The idler pull occursdue to a collection of transverse forces acting in the contact patch,the effect of which is called spin. Spin occurs at the three contactpatches, the points of contact where the balls contact the input disc34, the output disc 101, and the idler 18. The magnitude of theresultant forces from spin at the contact between the idler 18 and theballs 1 is minimal in comparison to that of the balls 1 and input andoutput discs 34, 101. Due to the minimal spin produced at the contactpatch of the idler 18 and ball 1 interface, this contact patch will beignored for the following explanation. Spin can be considered anefficiency loss in the contact patches at the input disc 34 and ball 1and also at the output disc 101 and ball 1. Spin produces a transverseforce perpendicular to the rolling direction of the balls 1 and discs34, 101. At a 1:1 ratio the transverse forces produced by spin, orcontact spin, at the input and output contact patches are equal andopposite and are essentially cancelled. There is no axial pull on theidler 18 in this condition. However, as the transmission 100 is shiftedtoward low for example, the contact patch at the input disc 34 and ball1 moves farther from the axis or pole of the ball 1. This decreases spinas well as the transverse forces that are produced perpendicular to therolling direction. Simultaneously the output disc 101 and ball 1 contactpatch moves closer to the axis or pole of the ball 1, which increasesspin and the resultant transverse force. This creates a situation wherethe transverse forces produced by spin on the input and output sides ofthe transmission 100 are not equal and because the transverse force onthe output contact is greater, the contact patch between the output disc101 and ball 1 moves closer to the axis of the ball 1. The farther thetransmission 100 is shifted into low the stronger the transverse forcesin the contacts become that are exerted on the ball 1. The transverseforces caused by spin on the ball 1 exert a force in the oppositedirection when shifting into high. The legs 2 attached to the ball axles3 transfer the pull to the shift guides 13 a, b, and because the shiftguides 13 a, b, are operably attached to the idler 18 and sleeve 19, anaxial force is transferred to the idler rod 171. As the normal forceacross the contact increases, the influence of spin increases at allratios and efficiency decreases.

Still referring to FIGS. 1 and 3, as the transmission 100 is shiftedinto low, the pull transferred to the idler rod 171 results in an axialforce toward the left, as viewed in FIG. 1, which causes the inputtorque to shift from the screw 35 to the perimeter ramps 61. As thetransmission 100 is shifted into extreme low, the idler rod 171 pullsmore strongly, causing relative movement between the central drive shaftramps 99 and the central bearing disc ramps 98 and shifts even moretorque to the perimeter ramps 61. This reduces the torque transmittedthrough the screw 35 and increases the torque transmitted through theperimeter ramps 61, resulting in an increase in axial force.

Referring to FIG. 6, a cutaway side view of an alternative axial forcegenerator 260 of the transmission 100 is disclosed. For purposes ofsimplicity, only the differences between the axial force generator 160previously described and the axial force generator 260 illustrated inFIG. 6 will be presented. The illustrated axial force generator 260includes one or more reversing levers 261. The reversing levers 261 aregenerally flat, irregularly shaped cam pieces each having an off-centermounted pivot hole with a first side radially inward of the pivot holeand a second side radially outside of the pivot hole. The first side ofthe reversing levers 261 each fit into the elongated slot 173 in theidler rod 171. When the transmission 100 is shifted toward low, the endof the elongated slot 173 contacts the first side of the reversinglevers 261 and the reversing levers 261 pivot on an axis produced by areversing pin 262 that is inserted into the pivot holes of the reversinglevers 261.

As the first sides are contacted by the end of the elongated slot 173,the first side of each of the reversing levers 261 moves toward theoutput side of the transmission 100 and the second side of the reversinglevers 261 moves toward the input side of the transmission 100 therebyfulfilling the cam function of the reversing levers 261. By increasingand decreasing the length of the first side and second side, thereversing levers 261 can be designed to decrease the distance that theymove axially toward the input side and increase the force they produce.The reversing levers 261 can be designed in this manner to create amechanical advantage to adjust the axial force that they produce. Attheir second sides, the reversing levers 261 each contact the outputside of the central screw ramps 298 when the transmission 100 is shiftedtoward low. The reversing levers 261 are each attached to a lever ring263 by the reversing pins 262, which can be pressed or threaded intoholes in the lever ring 263 to hold the reversing levers 261 inposition. The lever ring 263 is a ring shaped device that fits around,and slides axially along, the idler rod 171 and has one or morerectangular slots cut through it to allow for insertion and positioningof the reversing levers 261.

Still referring to the embodiment illustrated in FIG. 6, a set ofcentral screw ramps 299 is rigidly attached to and can be rotated by thescrew 35. The central screw ramps 299 of this embodiment are similar tothe central screw ramps 99 illustrated in FIG. 3, in that the centralscrew ramps 299 are formed as ramps on the second side of a disc havinga first side facing the output side and a second side facing the inputside. As the transmission 100 is shifted toward low, the second side ofthe reversing levers 261 pushes against the first side of the centralscrew ramps 299. The central screw ramps 299, which are splined to thedrive shaft 69 via the above-described spline 109, are rotated by thedrive shaft 69, are capable of axial movement along the longitudinalaxis 11, and are similar to the central drive shaft ramps 99 of theprevious embodiment, except that the central screw ramps 299 face theinput side of the transmission 100 rather than the output side. Thecentral screw ramps 299 contact an opposing set of central bearing discramps 298, which are free to rotate relative to the drive shaft 69 andare similar to the central bearing disc ramps 98 illustrated in FIG. 3,except that the central bearing disc ramps 298 face the output side ofthe transmission 100 rather than the input side. As the central screwramps 299 are pushed axially by the reversing levers 261 toward thecentral bearing disc ramps 298, relative rotation of the ramp faces ofthe central screw ramps 299 and central bearing disc ramps 298 isdeveloped that causes the bearing disc 60 to rotate to a point such thatthe perimeter ramps 61 become engaged, thereby shifting torque to theperimeter ramps 61 and increasing the amount of axial force that isgenerated.

Referring now to FIGS. 7 and 8, an alternative embodiment of thetransmission 100 of FIG. 1 is disclosed. For the purposes of simplicity,only those differences between the transmission 1700 of FIG. 8 and thetransmission 100 of FIG. 1 will be explained. The transmission 100 ofFIG. 1 includes one variator. The term variator in this sense can, insome embodiments, be used to describe the components of the transmission100 that vary the input to output speed ratio. The assemblies andcomponents comprising the variator 401 of the present embodimentillustrated in FIG. 7 include the ball/leg assembly 403 of FIG. 4, theinput disc 34, the output disc 101, the idler assembly 402 of FIG. 3,and the cage 89 of FIG. 5. It should be noted that all components andassemblies of the variator 401 can change to best fit the specificapplication of the transmission 1700, and in FIG. 7 generic forms of theassemblies and components comprising the variator 401 are depicted.

The embodiment of the transmission 1700 illustrated in FIG. 8 is similarto the transmission 100 of FIG. 1 but includes two variators 401. Thisconfiguration is beneficial for applications where high torque capacityis required in a transmission 1700 with a small diameter or overallsize. This configuration also eliminates bearings needed to support thebearing disc 114 and the output disc 101, thereby increasing overallefficiency. Due to the fact that the transmission 1700 has two variators401, each variator 401 has an output side and the transmission 1700 alsohas an output side. Thus there are three output sides and in thisconfiguration, the convention or marking of like components with an “a”and a “b” to differentiate between the input and output sides is notused. However, as illustrated in FIG. 8, the input side of thetransmission 1700 is to the right and the output is to the left.

Referring to FIGS. 8-9, a case 423 is illustrated that surrounds andencapsulates the transmission 1700. The case 423 is generallycylindrical and protects the transmission 1700 from outside elements andcontamination and additionally contains lubrication for properoperation. The case 423 is attached to an engine, frame, or other rigidbody (not shown) with standard fasteners (not shown), which fit throughcase holes 424. The case 423 is open on the input side, the side withthe case holes 424 or to the right as illustrated, to accept an inputtorque. Input torque is transmitted from an outside source to an inputshaft 425, which is a long, rigid, rod or shaft capable of transmittingtorque. The input shaft 425 transmits torque to a bearing disc 428 viasplines, keying, or other such manner. The bearing disc 428 is adisc-shaped rigid component capable of absorbing significant axialforces produced by the transmission 1700 and is similar in design to thebearing disc 60 illustrated in FIG. 1. An input shaft bearing 426 ispositioned coaxially over the input shaft 425 between a flange 429 onthe input end of the input shaft 425 and the bearing disc 428 to allow asmall amount of relative movement between the bearing disc 428 and theinput shaft 425. When the bearing disc 429 begins rotating, theperimeter ramps 61, ramp bearings 62, bearing cage 63, input disc ramps64, and input disc 34 rotate as previously described. This rotates theballs 1 in the first variator 420, the one on the input side.

Simultaneously, as the input shaft 425 rotates, a second input disc 431is rotated. The second input disc 431 is rigidly attached to the inputshaft 425, and can be keyed with a backing nut, pressed over the inputshaft 425, welded, pinned, or attached by other methods. The secondinput disc 431 is located on the output side of the transmission 1700,opposite the bearing disc 428. The second input disc 431 and the bearingdisc 428 absorb the considerable axial forces created by the perimeterramps 61, ramp bearings 62, and input disc ramps 64 that act as normalforces to prevent slippage at the ball/disc contact patches aspreviously described. Any of the other axial force generating mechanismsdescribed herein or known in the art can also be utilized by this andother embodiments. The second input disc 431 is similar in shape to theinput disc 34 previously described and upon rotation of the input shaft425; it rotates the balls 1 in the second variator 422. The secondvariator 422 is generally a mirror image of the first variator 420 andis positioned farther from the input side of the transmission 1700 sothat the first variator 420 is situated between it and the input side.In alternative embodiments, the second input disc 431 can be splined tothe input shaft 425 and driven by a structure similar to or the same asthe bearing disc 428 of the first input disc 34. Such splines can bestandard splines or ball splines. Such embodiments allow preloading ofthe transmission with a resilient washer between the second input disc431 and its respective bearing disc-like structure (not separatelyillustrated) where the bearings and ramps at the second side areremoved. Such a structure is known in the art and is described in thereferences described and incorporated below.

As previously described, the balls 1 in the first variator 420 rotatethe output disc 430 through their rolling contact with that component.The output disc 430, although serving the same function as the outputdisc 101 previously described, has two opposing contact surfaces andcontacts balls 1 on both variators 420, 422. From the cross sectionalview illustrated in FIG. 8, the output disc 430 can be shaped in ashallow arch or upside down shallow “V,” the ends of which have acontact surface to contact the balls 1 of the two variators 420, 422.The output disc 430 surrounds the second variator 422 and extends towardthe output side in a generally cylindrical shape. In the illustratedembodiment, the cylindrical shape of the output disc 430 continuestoward the output side of the transmission 1700 surrounding the secondinput disc 431 after which the diameter of the output disc 430 decreasesand then again becomes a generally cylindrical shape of a smallerdiameter as it exits the case 423. To hold the output disc 430concentric and align it with the first and second input discs 34, 431,annular bearings 434, 435, may be used to radially align the output disc431. A case bearing 434 is positioned in the bore of the case 423 andover the output disc 430 and an output disc bearing 435 is positioned inthe bore of the output disc 430 and over the input shaft 425 to provideadditional support. The output disc 430 can be made of two pieces thatare connected together to form the illustrated output disc 430. Thisallows for assembly of the second variator 422 inside the cylindricalshell of the output disc 430. As illustrated in FIG. 8, this can beaccomplished by use of two annular flanges along the large diameter ofthe output disc 430. In some embodiments, the annular flanges arelocated generally midway along the large diameter of the output disc430.

Referring now to FIGS. 8-10, the ball axles 433 of the transmission 1700are similar to the ball axles 3 previously described and perform thesame function. In addition, the ball axles 433 serve as the mechanism bywhich the balls 1 are tilted to vary the speed ratio of the transmission1700. The ball axles 433 are elongated on each of their respectiveoutput sides and extend through the walls of the output stators 435. Theoutput stators 435 are similar to the output stators 80 b previouslydescribed, but the multiple radial grooves 436 penetrate all the waythrough the walls of the output stators 435. The grooves 436 of theoutput stators 435 continue all the way through the output stator 435walls so that a series of equally spaced radial grooves 436 extendradially from near the bore at the center of the output stator 435 tothe perimeter. The ball axles 433 have iris rollers 407 positionedcoaxially over their elongated output ends. The iris rollers 407 aregenerally cylindrical wheels that are capable of rotating over the ballaxles 433 and are designed to fit inside the grooves 411 of an irisplate 409. The iris plate 409 is an annular disc or plate with a borethrough its center that fits coaxially about the longitudinal axis 11 ofthe transmission 1700. The iris plate 409 is of a thickness that isgreater than twice the thickness of each iris roller 407 and has anumber of iris grooves 411 extending radially outward from near the boreto near the perimeter of the iris plate 409. As the iris grooves 411extend radially, their angular position changes as well, so that as theiris plate 409 is rotated angularly about the longitudinal axis 11, theiris grooves 411 provide a camming function along their respectivelengths. In other words, the grooves 411 spiral out from near the borein the center of the iris plate 409 to respective points near itsperimeter.

The iris rollers 407 are radiused along their outside diameters, or havefillets on their outer corners, so that their diameters remain unchangedinside the grooves 411 of the iris plate 409 when the ball axles 433 aretilted. The iris plate 409 is of a thickness sufficient to allow irisrollers 407 from both variators 420, 422, to remain inside the grooves411 of the iris plate 433 at all shifting ratios. The iris grooves 411operate in traditional iris plate fashion and cause the ball axles 433to move radially inward or outward when the iris plate 409 is rotated.The iris plate 409 has a first side facing the first variator and asecond side facing the second variator and is coaxially positioned aboutthe longitudinal axis 11 of the transmission 1700 and over abuttingbosses on tubular extensions extending from the two output stators 435.The two output stators 435 can be attached to each other withconventional fasteners through axial holes (not illustrated) in thebosses of the output stators 435. The output stator 435 bosses have ahole through their centers and multiple holes positioned radiallyoutward from the center. In some embodiments, the bosses on the outputstators 435 form a space slightly wider than the iris plate 409 toprovide freedom of rotation for the iris plate 433 and some embodimentsutilize bearings between the bosses and the iris plate 409 to accuratelycontrol the position of the iris plate 409 between the output stators435. An iris cable 406 is attached to the first side of the iris plate409 near the outside diameter of the iris plate 409 and extendslongitudinally from the point of connection.

The iris cable 406 is routed through the output stator 435 of the firstvariator 420 in an orientation so that when it is pulled, it rotates theiris plate 409. The iris cable 406, after passing through an aperturenear the perimeter of the output stator 435 is routed through the case423 to the outside of the transmission 1700 where it allows for controlof the transmission ratio. An iris spring 408 is attached to the secondside of the iris plate 409 near its outside diameter. The iris spring408 is also attached to the output stator 435 of the second variator422. The iris spring 408 applies a resilient force that resists rotationof the iris plate 409 from tension applied by the iris cable 406. Whentension from the iris cable 406 is released, the iris spring 408 returnsthe iris plate 409 to its at-rest position. Depending upon theapplication of the transmission 1700, the iris plate 409 can beconfigured so that when the iris cable 406 is pulled the iris plate 409shifts the transmission 1700 to a higher transmission ratio, and whentension on the iris cable 406 is released the iris spring 408 shifts thetransmission 1700 to a low ratio. Alternatively, the iris plate 409 canbe configured so that when the iris cable 406 is pulled the iris plate409 shifts the transmission 1700 to a lower ratio, and when tension onthe iris cable 406 is released the iris spring 408 shifts thetransmission 1700 to a high ratio.

Referring to FIGS. 7 and 8, many embodiments of the transmission 1700having two variators 420, 422 require a high degree of accuracy in thealignment of the additional rolling elements of the transmission 1700.In some such embodiments, all of the rolling elements must be alignedwith one another or efficiency will suffer and the lifespan of thetransmission 1700 will be reduced. During assembly, the input disc 34,the output disc 430, the second input disc 431, and the idler assemblies402 are aligned on the same longitudinal axis. Additionally, the cage410, which in these embodiments consists of two cages 89 joined by theoutput stators 435 as previously described, must also be aligned on thelongitudinal axis to accurately position the ball/leg assemblies 403. Toaccomplish this simply and accurately, all rolling elements arepositioned relative to the input shaft 425. A first input stator bearing440 and a second input stator bearing 444 are positioned in the bores ofthe input stators 440, 444 and over the input shaft 425 to help alignthe cage 410. An output stator bearing 442 positioned in the bore of theoutput stators 435 and over the input shaft 425 also aligns the cage410. A first guide bearing 441 is positioned in the bore of the firstshift guide 13 b and over the input shaft 425 and a second guide bearing443 is positioned in the bore of the second shift guide 13 b and overthe input shaft 425 to align the first and second idler assemblies 402.

Referring to FIGS. 8 and 9, the cage 410 is attached to the case 423with the previously described case connectors 383 that fit into caseslots 421. The case slots 421 are longitudinal grooves in the case 423that extend to the input side of the case 423, the side of the case 423that is open. In the illustrated embodiment, the case is mostly closedon the output side, which is not shown in FIG. 8, but is open on theinput side and has a mounting flange extending radially from theotherwise cylindrical body of the case 423 with case holes 424 formounting the case 423. During assembly, the transmission 1700 can beinserted into the case 423 where the case connecters 383 are aligned inthe case slots 421 in order to resist torque applied to the cage 410 andprevent the cage 410 from rotating. Case connector holes 412 in the case423 allow fasteners to be inserted into corresponding holes in the caseconnectors 383 to fasten the cage 410 to the case 423.

EXAMPLES

Each of the variations that will now be described may have advantageouscharacteristics for particular applications. The variations can bemodified and controlled as necessary to achieve the goals for anyparticular application. Specific embodiments will now be described andillustrated that employ some of the variations described herein and/orlisted in the Tables provided in U.S. patent application Ser. No.10/788,736, which were incorporated above by reference. FIGS. 11 and 12illustrate one embodiment of a transmission 1100 that is a variationhaving one source of torque input and that supplies two sources oftorque output. As before, only the significant differences between theembodiment illustrated in FIGS. 11 and 12 and the previously illustratedand described embodiments will be described. Furthermore, the componentsillustrated are being provided to illustrate to one of skill in the arthow to provide power paths and torque output sources that have not beenpreviously illustrated. It is fully understood that many additionalcomponents can and will be utilized for operational embodiments, howeverfor simplification of the drawing, many such components have beenomitted or are represented schematically as boxes.

Referring to FIG. 11, torque is input through a drive shaft 1169 as inpreviously described embodiments. The drive shaft 1169 of thisembodiment is a hollow shaft having two ends and engaging on a first endwhatever prime mover is providing torque to the transmission 1100 andengaging at the second end a planet carrier 1130. The planet carrier1130 is a disc positioned coaxial with the longitudinal axis of thetransmission 1100 that interfaces at its center with the drive shaft1169 and extends radially to a radius near that of the inner side of thecase 1140 of the transmission 1100. In this embodiment, the case 1140 isstationary and is fixed to some supporting structure of the vehicle orequipment upon which it is utilized. A radial carrier bearing 1131 islocated between the inner surface of the case 1140 and the outer edge ofthe planet carrier 1130. The carrier bearing 1131 of some embodiments isa radial bearing that provides radial support to the planet carrier1130. In other embodiments, the carrier bearing 1131 is a compoundbearing providing both radial and axial support to the planet carrierpreventing cocking as well as radial or axial movement.

A plurality of planet shafts 1132 extend from the planet carrier 1130from a radial position between the center and the outer edge of theplanet carrier 1130. The planet shafts 1132 extend axially toward theoutput end of the transmission 1100 and are generally cylindrical shaftsthat connect the planet carrier 1130 to the input disc 1134 and eachform an axis about which a respective planet gear 1135 rotates. Theplanet shafts 1132 can be formed into the input side of the input disc1134 or the planet carrier 1130 or can be threaded into either the inputdisc 1134 or the planet carrier or can be attached by fasteners orotherwise. The planet gears 1135 are simple rotary gears that aresupported by and rotate about the planet shafts 1132 and manyembodiments utilize bearings between the planet gears 1135 and theplanet shafts 1132. They can have straight teeth or helical teeth,however where helical gears are used, thrust bearings are used to absorbthe axial thrust developed by the transmission of torque by the planetgears 1135.

Still referring to the embodiment illustrated in FIG. 11, the planetgears 1135 engage at two areas along their respective circumferences atany one time as they rotate about their respective axes. At a firstcircumferential position located farthest away from the longitudinalaxis of the transmission 1100, each planet gear 1135 engages a ring gear1137. The ring gear 1137 is an internal gear formed on or attached tothe inner surface of the case 1140. In some embodiments, the ring gear1137 is a set of radial teeth formed on the inner surface of the ringgear 1137 and extending radially inward such that the planet gears 1135can engage with its teeth and ride along the inner surface of the ringgear 1137 as they orbit the longitudinal axis of the transmission 1100.At a circumferential point of the planet gears 1135 generally oppositethe radially outward most part, the ring gears 1135 engage a sun gear1120. The sun gear 1120 is a radial gear that is mounted coaxially aboutthe longitudinal axis of the transmission 1100 at the center of theplanet gears 1135 and engages all of the planet gears 1135. As theplanet carrier 1130 rotates the planet gears 1135 about the sun gear1120, the planet gears 1135 are rotated about their respective planetshafts 1132 by their engagement with the ring gear 1137 and thereforeboth orbit the sun gear 1120 and rotate on their own shafts as theyorbit. This results in a rotational energy that is transmitted to thesun gear 1120 that is at a greater speed than the speed input by thedrive shaft 1169.

In the embodiment illustrated in FIG. 11, the drive shaft 1169 alsodrives the input disc 1134 via the planet carrier 1130 and the planetshafts 1132. However, the planet gears 1135 also drive the sun gear 1120so that the power from the planet carrier is distributed to the inputdisc 1134 and the sun gear 1120. The sun gear 1120 is rigidly connectedto and rotates the cage 1189 of this embodiment. The cage 1189 issimilar to the embodiments described above, and therefore not all of thecomponents have been illustrated to simplify the drawing and improve theunderstanding of this description. The cage 1189, as in otherembodiments, positions the balls 1101 about the longitudinal axis of thetransmission 1100 and because the cage 1189 of this embodiment rotatesabout its axis, it causes the balls 1101 to orbit the longitudinal axisof the transmission 1100. The input disc 1134, which is similar to thosedescribed above, provides an input torque to the balls 1101 in the samemanner as in previous embodiments. However the sun gear 1120 alsoprovides an input torque to the balls 1101 by rotating the cage 1189,which is added to the input from the input disc 1134. In thisembodiment, the output disc 1111 is rigidly fixed to the case 1140 anddoes not rotate about its axis. Therefore, the balls 1101 roll along thesurface of the output disc 1111 as they orbit the longitudinal axis ofthe transmission 1100 and rotate about their respective axes.

The balls 1101 cause the idler 1118 to rotate about its axis as in otherembodiments, however in this embodiment, the idler 1118 includes anidler shaft 1110 that extends out beyond the hole formed by the innerdiameter of the output disc 1111. The balls 1101 drive the idler 1118,which in turn drives the idler shaft 1110, which provides the firsttorque output from the transmission 1100. As illustrated in FIG. 12, theidler shaft 1110 can be of a cross-sectional shape that lends itself toeasier coupling with devices that would take power from the idler shaft1110 and in some embodiments, as illustrated, the shape is hexagonal,although any such shape can be used. It is noted that due to axialmovement of the idler 1118 during shifting as described below, the idlershaft 1110 moves axially during shifting of the transmission 1100. Thismeans that the couple between the idler shaft 1110 and the output device(not shown) of this design allows for axial motion of the idler shaft1118. This can be accomplished by allowing a slightly larger outputdevice shaft such that the idler shaft 1110 is free to move within theoutput device, or by the use of a splined output idler shaft 1110, suchas by ball spline. Alternatively the idler 1118 can be splined to theidler shaft 1110 in order to maintain the axial position of the idlershaft 1110.

Still referring to FIGS. 11 and 12, the cage 1189 can provide an outputpower source as well. As illustrated, the cage 1189 can be connected onits inner diameter on the output side to a cage shaft 1190. In theillustrated embodiment, the cage shaft 1190 is formed at its end into anoutput gear or spline to engage and supply power as a second outputsource.

As illustrated in FIG. 11, various bearings can be implemented tomaintain the axial and radial position of various components in thetransmission 1100. The cage 1189 can be supported in its place by cageoutput bearings 1191, which are either radial bearings to provide radialsupport or are preferably combination bearings to maintain both axialand radial position of the cage with respect to the case 1140. The cageoutput bearings 1191 are assisted by cage input bearings 1192 which arealso radial or preferably combination radial-thrust bearings andposition the cage 1189 relative to the input disc 1134. In embodimentsutilizing an axial force generator where the input disc 1134 is subjectto slight axial movement or deformation, the cage input bearings 1192are designed to allow for such movement by any mechanism known in theindustry. One embodiment utilizes an outer bearing race that is splinedto the inner diameter of the input disc 1134, by a ball spline forexample, in order that the input disc 1134 can move axially slightlyrelative to the outer race of the cage input bearing 1192.

The shifting mechanism of the embodiment illustrated in FIG. 11 isslightly varied from the embodiments illustrated previously in order toallow for the transmission of output torque supplied by the idler 1118.In this embodiment, the idler 1118 initiates the shifting by being movedaxially upon actuation by the shift rod 1171 and in turn moves the shiftguides 1113 axially causing the shifting mechanism to change the axes ofthe balls 1101 as described above. The shift rod 1171 does not threadinto the idler 1118 in the illustrated embodiment, however and onlycontacts the idler 1118 via idler input bearings 1174 and idler outputbearings 1173. The idler input and output bearings 1174, 1173,respectively, are combination thrust and radial bearings that positionthe idler 1118 both radially and axially along the longitudinal axis ofthe transmission 1100.

When the shift rod 1171 is moved axially toward the output end, theinput idler bearing 1174 applies axial force to the idler, therebymoving the idler axially to the output end and initiating a change inthe transmission ratio. The shift rod 1171 of the illustrated embodimentextends beyond the idler 1118 through an inner diameter formed in thecenter of the sun gear 1120 and into the second end of the drive shaft1169 where it is held in radial alignment within the drive shaft 1169 byan idler end bearing 1175. The shift rod 1171 moves axially within thedrive shaft 1169 however and therefore the idler end bearing 1175 ofmany embodiments allows for this motion. As described before, many suchembodiments utilize a splined outer race that engages a mating splineformed on the inner surface of the drive shaft 1169. This splined raceallows the race to slide along the inner surface of the drive shaft 1169as the shift rod 1171 is moved axially back and forth and still providesthe radial support used to assist in radially aligning the shift rod1171. The inner bore of the sun gear 1120 can also be supported radiallywith respect to the shift rod 1171 by a bearing (not illustrated)located between the shift rod 1171 and the sun gear 1120. Again eitherthe inner or outer race could be splined to allow for the axial motionof the shift rod 1171.

When the idler 1118 of the embodiment illustrated in FIG. 11 is movedaxially to shift the transmission 1100, the idler 1118 moves the shiftguides 1113. In the illustrated embodiment, the shift guides 1113 areannular rings coaxially mounted about each end of the idler 1118. Theillustrated shift guides 1113 are each held in radial and axial positionby an inner shift guide bearing 1117 and an outer shift guide bearing1172. The inner and outer shift guide bearings of this embodiment arecombination bearings providing both axial and radial support to theshift guides 1113 in order to maintain the axial and radial alignment ofthe shift guides 1113 in relation to the idler 1118. Each of the shiftguides 1113 can have a tubular sleeve (not shown) that extends away fromthe idler 1118 so that the shift guide bearings 1117 and 1172 can befurther apart to provide additional support to the shift guides 1113, asneeded. The shift rod 1171 can be moved axially by any known mechanismfor causing axial motion such as an acme threaded end acting as a leadscrew or a hydraulically actuated piston or other know mechanisms.

Referring to FIGS. 11 and 12, the paths of power through thetransmission 1100 follow to parallel and coaxial paths. Initially, powerenters the transmission 1100 via the drive shaft 1169. The power is thensplit and transmitted through the planet carrier 1130 both to the inputdisc 1134 and to the sun gear 1120 via the planet gears 1135. The latterpower path is then transmitted from the sun gear 1120 to the cage 1189and out of the transmission 1100 via the cage shaft 1189. This powerpath provides a fixed transmission ratio from the drive shaft based uponthe dimensions of the sun gear 1120 and the planet gears 1135. Thesecond power path is from the planet carrier 1130 through the planetshafts 1132 and to the input disc 1134. This power path continues fromthe input disc 1134 to the balls 1101 and from the balls 1101 to theidler shaft 1118 and out of the transmission 1100 through the idlershaft 1110. This unique arrangement allows the two power paths to betransmitted through the transmission 1100 not only in parallel paths butthrough coaxial paths. This type of power transmission allows for asmaller cross-sectional size for the same torque transmission and leadsto significant size and weight reductions and to a much simpler designcompared to other IVTs.

The embodiment illustrated in FIGS. 11 and 12, illustrates to one ofskill in the art how the idler 1118 can be used as a power output aslisted above and how to combine the planetary gear set with the CVT asdescribed above. It is expected that variations of this design can beutilized while achieving the various combinations described, and suchalternate designs cannot all be illustrated herein due to theoverwhelming number of combinations listed that are available. It isalso understood that the axial force generators provided herein can alsobe utilized with this embodiment, but for simplification these devicesare not illustrated. For embodiments utilizing one of the axial forcegenerators described herein, or another, it is expected that thecomponents of the axial force generator can be implemented between wherethe planet shafts 1132 connect to the input disc 1134, although otherarrangements can be employed as well. In such embodiments, the parallelpath is coaxial with the axis of the transmission 1100 allowing for amuch smaller transmission 1100 for the same torque transmission andthereby leading to reduced weight and space of such embodiments. FIGS.11 and 12 illustrate one combination in order to show how rotationalpower might be taken from the various components of the transmission invarious embodiments. Obviously, those of skill in the art will easilyunderstand how other configurations provided herein can be achieved byvarying the connections, and it would be unnecessarily burdensome andvoluminous to illustrate all or even more combinations for the simplepurpose of illustrating the combinations described. The embodimentsshown in FIGS. 11 and 12 can therefore be modified as necessary toproduce any of the variations listed above or below without the need fora separate non-coaxial parallel power path.

Referring now to FIG. 13, an alternative embodiment of a transmission1300 is illustrated. In this embodiment, the output disc 1311 is formedas part of the case of previous embodiments to form a rotating hub shell1340. Such an embodiment is suited well for applications such asmotorized two wheel vehicles or a bicycle. As mentioned before, only thesubstantial differences between this embodiment and the previouslydescribed embodiments will be described in order to reduce the size ofthis description. In this embodiment, the input torque is supplied to aninput wheel 1370, which can be a pulley for a belt or a sprocket for achain or some similar device. The input wheel 1370 is then attached tothe outside of a hollow drive shaft 1369 by press fitting or splining orsome other suitable method of maintaining angular alignment of the tworotary components. The drive shaft 1369 passes through a removable endof the hub shell 1340 called the end cap 1341. The end cap 1341 isgenerally an annularly shaped disc having a bore through its center toallow passage of the drive shaft 1369 into the inside of thetransmission 1300 and having an outer diameter that mates with the innerdiameter of the hub shell 1340. The end cap 1341 can be fastened to thehub shell 1340 or it can be threaded into the hub shell 1340 toencapsulate the inner components of the transmission 1300. The end cap1341 of the illustrated embodiment has a bearing surface andcorresponding bearing on the inside of its outer diameter forpositioning and supporting the axial force generator 1360 and has abearing surface and corresponding bearing at its inner diameter thatprovides support between the end cap 1341 and the drive shaft 1369.

The drive shaft 1369 fits over and rotates about an input axle 1351,which is a hollow tube that is anchored to the vehicle frame 1315 by aframe nut 1352 and that provides support for the transmission 1300. Theinput axle 1351 contains the shift rod 1371, which is similar to theshift rods described in previous embodiments, such as that illustratedin FIG. 1. The shift rod 1371 of this embodiment is actuated by a shiftcap 1343 threaded over the end of the input axle 1351 that extendsbeyond the vehicle frame 1315. The shift cap 1343 is a tubular cap witha set of internal threads formed on its inner surface that mate with acomplimentary set of external threads formed on the outer surface of theinput axle 1351. The end of the shift rod 1371 extends through a holeformed in the input end of the shift cap 1343 and is itself threadedallowing the shift cap 1343 to be fastened to the shift rod 1371. Byrotating the shift rod 1371 its threads, which may be acme threads orany other threads, cause it to move axially and because the shift rod1371 is fastened to the shift cap 1343, the shift rod 1371 is movedaxially as well, actuating the movement of the shift guides 1313 and theidler 1318, thereby shifting the transmission 1300. In otherembodiments, the shift rod 1371 does not rotate but contacts the shiftcap 1343 via bearings so that when the shift 1343 cap rotates, the shiftrod 1371 can remain in its same angular position while it is positionedaxially by the shift cap 1343.

Still referring to the embodiment illustrated in FIG. 13, the driveshaft 1369 rides on and is supported by the input axle 1351 and one ormore shaft support bearings 1372, which can be needle bearings or otherradial support bearings. The drive shaft 1369 provides torque to anaxial force generator 1360 as in previous embodiments. Any of the axialforce generators described herein can be used with this transmission1300, and this embodiment utilizes a screw 1335 that is driven by thedrive shaft 1369 by splining or other suitable mechanism thatdistributes torque to the drive disc 1334 and to a bearing disc 1360, asin any of the previous embodiments. In this embodiment, a drive seal1322 is provided between the inner diameter of the input wheel 1370 andthe outer diameter of the input axle 1351 beyond the end of the driveshaft 1369 in order to limit the amount of foreign material that isadmitted to the inside of the transmission 1300. Another seal (notshown) can be used between the case cap 1342 and the input wheel tolimit foreign particle infiltration from between the end cap 1341 andthe drive shaft 1369. The drive seal 1322 can be an o-ring seal, a lipseal or any other suitable seal. The illustrated embodiment alsoutilizes a similar cage 1389 as previously described embodimentshowever, the illustrated transmission 1300 utilizes axle bearings 1399to support the balls 1301 on their axles 1303. The axle bearings 1399can be needle bearings or other suitable bearings and reduce thefriction between the balls and their axles 1303. Any of the variousembodiments of balls and ball axles described herein or known to thoseof skill in the art can be used to reduce the friction that isdeveloped.

Still referring to the embodiment illustrated in FIG. 13, the cage 1389and the shift rod 1371 are supported on the output side by an outputaxle 1353. The output axle 1353 is a somewhat tubular support memberlocated in a bore formed in the output end of the hub shell 1340 andbetween the cage 1389 and the output side vehicle frame 1315. The outputaxle 1353 has a bearing race and bearing formed between its outerdiameter and the inner diameter of the hub shell 1340 to allow forrelative rotation of the two components as the output axle 1353 providessupport to the output side of the transmission 1300. The output shaft isclamped to the vehicle frame 1315 by an output support nut 1354.

As is illustrated in FIG. 13, this transmission 1300 is shifted byapplying tension to the shifting cord 1355 that is wrapped around andwhich applies rotational force to the shift cap 1343. The shift cord1355 is a tether capable of applying a tension force and is actuated bya shifter (not shown) used by the operator to shift the transmission1300. In some embodiments the shift cord 1355 is a guide wire capable ofboth pulling and pushing so that only one coaxial guide line (not shown)needs to be run to the shifter from the transmission 1300. The shiftingcord 1355 is conducted by housing stops 1316 to and from the shift,capfrom the shifter used by the operator. The housing stops 1316 areextensions from the vehicle frame 1315 that guide the shifting cord 1355to the shift cap 1343. In the illustrated embodiment, the stop guides1316 are somewhat cylindrically shaped extensions having a slot formedalong their length through which the shifting cord 1355 passes and isguided. In other respects, the transmission 1300 illustrated in FIG. 13is similar to other embodiments illustrated herein.

Another transmission 1400 that is similar to the one illustrated in FIG.13 is illustrated in FIG. 14. In this embodiment, the output disc 1411is also fixed to the case 1440, however, the case 1440 is fixed and doesnot rotate. In this embodiment, however, similar to the embodimentillustrated in FIG. 11, the cage 1489 is free to rotate relative to theoutput disc 141 1 and the case 1440. This means that the output is againthrough the idler 1418. In this embodiment the idler 1418 is attached toa moveable output shaft 1453 similar to that described in the embodimentof FIG. 11. The output shaft 1453 terminates at the far end on theoutput side in an output spline 1454, which allows coupling of themoveable output shaft 1453 to whatever device is being supplied withtorque by the transmission 1400. In this embodiment, torque is suppliedto the transmission 1400 via the input shaft 1472 by a chain andsprocket (not shown), by an input gear (not shown) or by other knowncoupling means. The torque then passes through to the input disc 1434 asdescribed in the preceding embodiment. However, as described, withreference to FIG. 13, the balls 1401 ride along the surface of theoutput disc 1411 and transfer torque to the idler 1418.

As with the embodiment illustrated in FIG. 11, by supplying the torqueoutput via the idler 1418, the shift guides 1413 of this embodiment aresupported by bearings 1417 on the outer surface of the output shaft1453. This transmission 1400 is shifted by moving the shift rod 1471axially and is actuated by an actuator 1443. The actuator can be theshift cap of FIG. 13, or a wheel or gear controlled by an actuatingmotor or manually, or the actuator 1443 can be any other mechanism foraxially positioning the shift rod 1471, such as one or more hydraulicpistons. In some embodiments, the axial force generator 1460 and theshifting mechanism illustrated below in FIG. 15 is utilized. Throughthis embodiment, a very high transmission ratio can be achieved at avery high efficiency and with very little frictional losses whencompared with other transmission types.

Referring now to FIG. 15, another alternative axial force generator 1560is illustrated. In this embodiment the screw 1535 is located in theinner bore of the bearing disc (not shown) instead of the input disc1534. In this embodiment, the screw 1535 is driven directly by the driveshaft (not shown) via splines 1575, which mate with matching splinesfrom the drive shaft. The screw 1535 then distributes torque to theinput disc 1534 via central screw ramps 1598 and central disc ramps 1599and to the bearing disc via its threads 1576 and a corresponding set ofinternal threads (not shown) formed on the inner surface of the bore ofthe bearing disc. As the screw 1535 is rotated by the drive shaft, a setof central screw ramps 1598 that are formed on the output end of thescrew 1535 is rotated and engages and rotates a complimentary set ofcentral disc ramps 1599. The central disc ramps 1599 are formed on athrust washer surface formed on the input side of the input disc 1534near its inner diameter, and as they are rotated by the central screwramps 1598, the central disc ramps 1599 begin to apply torque and axialforce to the input disc 1534 from the reaction of the angled surfaces ofthe central ramps 1598, 1599. Additionally, the rotation of the screw1535 causes its threads 1576 to engage with the threads of the bearingdisc to begin to rotate the bearing disc.

Referring now to FIG. 15 in the illustrated embodiment, the axial forcegenerator 1560 is directly affected by the position of the idler 1518.In this embodiment, the idler assembly has a tubular extension called apulley stand 1530 that extends from the input side thrust guide 1513 andthat ends near the input disc 1534 in an annular extension spreadingradially outward. A linkage assembly made up of a fixed link 1516, afirst link pin 1517, a short link 1512, a cam link 1514, a cam link pin1515 and a stationary cam pin 1523 extends axially toward the screw 1535from the pulley stand 1530 and positions the screw 1535 axiallydepending on the transmission ratio. The links 1516, 1512 and 1514 aregenerally elongated struts. The fixed link 1516 extends from the inputend of the pulley stand 1530 toward the screw 1535 and is connected tothe intermediate short link 1512 by the first link pin 1517. The firstlink pin 1517 forms a floating pin joint between the fixed link 1516 andthe short link 1512 such that the short link 1512 can rotate about thefirst link pin 1517 as the two links 1516, 1512 move axially duringshifting. The short link 1512 is then connected at its other end to thecam link 1514 by a cam link pin 1515 and thereby forms a floating pinjoint. The cam link 1514 is fixed axially by a stationary cam pin 1523that is fixed to the axle 1571 or another stationary component and formsa pin joint about which the cam link 1514 rotates as the idler 1518moves axially.

In the following description, for simplification of the drawing, thebearing disc 60, ramp bearings 62, perimeter ramps 61 and input discramps 64 of FIG. 1 are not separately illustrated, but similarcomponents can be utilized to fulfill similar functions in the presentembodiment. When the axial force generator 1560 illustrated in FIG. 15is in a high transmission ratio, the idler 1518 is located at an axialposition at its far input side and therefore the fixed link 1516 is alsolocated at its farthest axial point toward the input side. The firstlink pin 1517, the short link 1512 and the second link pin 1521 are alllocated towards the input side and therefore the cam link 1514 isoriented about the stationary cam pin 1523 such that its cam surface(not separately illustrated) is rotated away from the screw 1535. Thecam link 1514 applies cam force to the screw 1535 when it is rotatedabout its fixed stationary cam pin 1523 axis to force the screw towardthe output side when in low transmission ratios. However in lowtransmission ratios, as illustrated, the cam surface of the cam link1514 is rotated away from the screw 1535. This allows the screw 1535 tosettle at its farthest point towards the output side and results in thebearing disc rotating counter-clockwise, looking from the input sidetowards the output side, about the screw 1535 in order to maintainengagement with the screw threads 1576. As this occurs the bearing rampsare rotated counter-clockwise allowing the disc bearings (notillustrated here but similar to those previously described with respectto FIG. 1) to roll to a point between the bearing disc ramps and theramps of the input disc 1534 where the bearings provide little or noaxial force.

Meanwhile, due to the extreme position of the screw 1535 to the left asviewed in FIG. 15, the central screw ramps 1598 are engaged with thecentral disc ramps 1599 fully such that the input disc 1534 is rotatedclockwise slightly to allow the axial position of the screw 1535 in itsfarthest output side position. The rotation of the input disc 1534 inthis manner means that the input disc ramps have rotated in an oppositedirection of the bearing disc ramps thereby amplifying the effect ofunloading the perimeter ramps and bearings. In such a situation, themajority or all of the axial force is being applied by the central ramps1598, 1599 and little if any axial force is generated by the perimeterramps.

As the idler 1518 moves toward the output side to shift to a lowertransmission ratio, the linkage assembly becomes extended as the fixedlink 1516 moves axially away from the screw 1535, and the cam link 1514is rotated about the stationary cam pin 1523. As the cam link 1514 isrotated about the cam link pin 1523, the axial motion of the fixed link1516 acts upon one end of the cam link 1514, while the other end movestoward the screw 1535, thereby reversing the direction of the axialforce applied by the fixed link 1516. By adjusting the lengths of wherethe various connections are made to the cam link 1514, the axial forceapplied by the fixed link 1516 can be diminished or magnified by leveraction. The cam end of the cam link 1514 applies an axial force to athrust washer 1524 on the output side of the screw 1535. The thrustwasher 1524 engages a screw thrust bearing 1525 and a bearing race 1526to supply the resultant axial force to the screw 1535. In response, thescrew 1535 moves axially toward the input side and its threads 1576rotate the bearing disc clockwise, looking from input side to outputside, causing the perimeter ramps to rotate so that the ramp bearingsare moved along the perimeter ramps to a position where they begin todevelop axial force. At the same time, due to the axial movement of thescrew 1535 toward the input side, the central screw ramps 1598 aredisengaged from the central disc ramps 1599 and the input disc 1534rotates, relative to the screw 1535, counter-clockwise, again aiding themovement of the perimeter ramp bearings to a position to generate axialforce. Through this lever action of the linkage assembly, the axialforce generator 1560 of this embodiment efficiently distributes theaxial force and torque between the central ramps 1598, 1599 and theperimeter ramps.

Also illustrated in FIG. 15 is an alternative leg assembly to that ofFIG. 3 that allows for a reduced overall size of the transmission. Inthe illustrated embodiment, the rollers 1504 are positioned radiallyinward on the legs 1502 as compared to the legs 2 of FIG. 3.Additionally, the input disc 34 and output disc (not shown) contact theballs 1 at a point closer to their axes which reduces the load on theidler 18 and enables the transmission to carry more torque. With thesetwo modifications, the input disc 34 and output disc (not shown) of thisembodiment can be reduced in total diameter to a diameter substantiallythe same as the farthest opposing points on two diametrically opposingballs 1501 of this embodiment as illustrated by the line “O.D.”

Another feature of the embodiment illustrated in FIG. 15 is a modifiedshifting assembly. The rollers 1504 of this embodiment are formed aspulleys each with a concave radius 1505 at its outer edge instead of aconvex radius. This allows the rollers 1504 to fulfill their function ofaligning the ball axles 1503 but also allows them to act as pulleys tochange the axes of the ball axles 1503 and the balls 1501 in order toshift the transmission. The flexible cables 155 described with respectto FIGS. 1 and 5, or similar shifting cables can be wrapped around therollers 1504 of one side so that when a tension is applied, thoserollers 1504 come closer together, thereby shifting the transmission.The shifting cables (not illustrated in FIG. 15) can be guided throughthe cage (item 89 of FIG. 1) to the rollers 1504 by guide rollers 1551,which in the illustrated embodiment are also pulleys mounted on guideshafts 1552 to the output end of the pulley stand 1530.

In some embodiments, the guide rollers 1551 and the guide shafts 1552are designed to allow the axis of the guide rollers 1551 to pivot inorder to maintain a pulley-type alignment with the rollers 1504 as theball axles 1503 change their angles with respect to the axis of thetransmission. In some embodiments, this can be accomplished by mountingthe guide shafts 1552 to the pulley stand 1530 with pivot joints ortrunnions, or any other known method. In this embodiment, one shiftcable can act on one set of rollers 1504 on either the input side or theoutput side of the balls 1501 and a spring (not shown) biases the ballaxles 1503 to shift in the other direction. In other embodiments, twoshifting cables are used with one on one side that draws the rollers1504 on its side radially inward and another cable on the opposite endof the balls 1501 that draws the rollers 1504 on its respective sideradially inward shifting the transmission thusly. In such an embodimenta second pulley stand 1530 or other suitable structure is formed on theoutput end of the shift guides 1513 and a corresponding set of guideshafts 1525 and guide rollers 1551 is mounted on that second pulleystand 1530. The cables (not shown) of such embodiments pass throughholes or slots (not shown) formed in the axle 1571 and out of thetransmission via the axle 1571. The cables can pass out of either orboth of the ends of the axle 1571 or they can pass out of additionalholes formed through the axle 1571 axially beyond either or both theinput disc (not shown) and the output disc (also not shown), or the hub(not shown) it the output disc is a rotating hub. The holes and or slotsthrough which the cables pass are designed to maximize the life of thecable material through the use of radiused edges and pulleys, and suchdesign elements are used in various locations of the axle andtransmission for conveyance of the cable.

Servo Control Systems

The embodiments described herein can be used in a servo control system,such as, for example, in a power-assisted steering system. The variatorand transmission can be utilized at or near its zero output transmissionratio to correct angular misalignments of a control shaft and thetransmission's output shaft. In some steering embodiments, thecontinuously variable transmission is arranged coaxially with a steeringwheel or other rotary actuating member and a steering mechanism suchthat the continuously variable transmission reacts and corrects anangular misalignment between the output shaft of the transmission andthe steering shaft connected to the steering wheel.

FIG. 16 a illustrates one embodiment of a servo control system used as apower assisted steering system 1600. A steering wheel 1602 provides adirect input to a steering pinion 1675 of a rack and pinion steeringmechanism through a steering shaft 1610. The steering shaft providestorsional flexing as will be described later to provide shifting controlsignals for the power assisted steering system 1600. The steering system1600 includes the output of a constant speed electric motor 1620 that isconnected to the planet carrier 1603 via motor output gear 1621. Whilethe motor output gear 1621 engages in this embodiment by meshing withexternal teeth formed on the outer edge of the planet carrier 1603, themotor 1620 can provide input torque to the planet carrier 1603 by anymechanism known in the art such as, for example, pulley and sprocket.The planet carrier 1603 in this embodiment is connected to each of a setof planet gears 1606, which rotate about a plurality of shafts thatextend from the planet carrier 1603, and also to the input disc 1634.The planet gears 1606 engage at their radially outward side with thering gear 1607, which is fixed and does not rotate, and at theirradially inward side with the sun gear 1605. Therefore, the planet gears1606 rotate the sun gear 1605 at a fixed rotation rate determined by thespeed of the electric motor 1620, the radii of the planet gears 1606 andthe radius of the sun gear 1605.

The variator 1640 of this embodiment acts as a variable planetary gearset in series with the fixed planetary gear set made up of the ring gear1607, the planet gears 1606 and the sun gear 1605. The sun gear 1605drives the cage 1689 of the variator 1640 and the planet carrier 1603drives the input disc 1634. The torque provided to the cage 1689 and thetorque provided to the input disc 1634 are summed by the variator 1640and transmitted to the output disc 1601. The output disc 1601 drives apower assist shaft 1615 in this embodiment, which adds the additionaltorque to assist the manual steering applied to the steering wheel 1601in this embodiment.

In other embodiments, the motor 1620 provides input torque to the sungear 1605 directly, which drives the planet gears 1606 and the planetcarrier 1603, thereby driving the input disc 1634. In such embodiments,the rotational speed transmitted to the input gear 1634, and thereforethe balls (not separately referenced in this figure) and the idler 1618is significantly reduced.

In still other embodiments of the steering system 1600, the planetarygear set is removed. The motor 1620 of this embodiment provides inputdirectly to the cage 1689 and the input disc 1634 is fixed to the case(not separately identified). In such embodiments, the construction anddesign of the steering system 1600 is simplified:

Still referring to FIG. 16 a, the amount and rotational direction of theoutput assisting torque applied by the power assist shaft 1615 isdetermined by the transmission ratio of the variator 1640. The system1600 accomplishes the control of the transmission ratio through amechanical connection of the variator 1640 and the steering wheel 1602.As a driver turns the steering wheel 1601 to turn the steering wheels ofa vehicle, the steering shaft 1610 is rotated and thereby begins torotate the steering pinion 1675. In a typical steering system, thesteering pinion 1675 engages a steering rack (not shown) that is typicalof a rack and pinion steering system. The rack is connected at each endvia steering tie rods (not shown) to steering arms on the hubs of thesteering wheels of the vehicle (all not shown). Such components arestandard items in steering systems.

As the driver begins to apply torque to the steering shaft 1610 byturning the steering wheel, the steering shaft 1610 transmits thattorque to the steering pinion 1675, which engages the rack to convertthe rotational torque of the steering wheel 1601 into linear motion ofthe ends of the rack, which is then transferred to the wheels via thetie rods and steering arms. This applies a moment to the wheel thattends to rotate each wheel about its turning axis of rotation, which isresisted by the frictional contact of the tire and the road. As the roadresists the turning of the tire, the torque applied to the steeringshaft 1610 must be increased to cause the wheels to turn. The steeringshaft is designed with a flexural modulus that allows the steering shaftto begin to torsionally flex at a desired torque level in response tothe torque applied to the steering wheel 1602. Because the power assistshaft 1615 is attached to the steering pinion 1675 coaxially with thesteering shaft 1610, as the steering shaft 1610 begins to torsionallyflex, as just described, it becomes angularly misaligned with the powerassist shaft 1615. This angular misalignment is used in this embodimentto shift the variator 1640.

In the embodiment illustrated in FIG. 16 a, a generally tubular shifter1632 is angularly aligned with and axially moveable along the steeringshaft 1610. The shifter 1632 is a relatively short tube that is splinedto, or otherwise angularly aligned with, a portion of the steering shaft1610. The shifter 1632 has a first end near the idler 1618 and a secondend facing away from the idler 1618. The first end of the shifter 1632is designed to dynamically connect to the idler 1618 so that as theidler 1618 rotates during operation of the variator 1640, the shifter1632 can move the idler 1618 axially in order to shift the transmissionratio of the variator 1640. In the illustrated embodiment, the first endof the shifter 1632 has a flange extending radially outward from therest of the tubular body of the shifter. The first end of this shifter1632 fits within a recess 1619 of the idler 1618 and is held within theidler 1618 by a retention ring 1621. The retention ring 1621 can be asnap ring 1621 or can have a threaded outer diameter to screw into therecess 1619. Thrust bearings 1617 allow the idler 1618 to rotaterelative to the shifter 1632 while allowing the shifter 1632 to apply anaxial force to move the idler 1618 axially, in order to shift the idler1618.

Still referring to FIG. 16 a, a steering pin 1630 extends in atransverse manner through the shifter 1632 and fits into a spiralingslot formed in the power assist shaft 1615. The steering pin 1630 slidesalong the spiral slot in the power assist shaft 1615. As the steeringshaft 1610 begins to torsionally flex, the shifter 1632 and the steeringpin 1630 begin to become angularly misaligned with the power assistshaft 1615. The spiral shape of the slot in the power assist shaft 1615causes a camming effect that moves the shifter 1632 axially, dependingon the direction of the angular misalignment. The axial movement of theshifter 1632 drives the idler 1618 to move axially and shift the powersteering system 1600 to a transmission ratio that produces an output inthe output disc 1601, which output acts to correct the angularmisalignment. As the angular misalignment is corrected, as the vehicleattains the appropriate turning attitude, the steering pin 1630, theshifter 1632 and the idler 1618 begin to ease back to their respectivezero-output positions and the output disc 1601 provides less or nooutput torque.

When the power assist shaft is applying no torque, such as when avehicle is traveling straight, the variator 1640 is at a ratio providingzero output. When the power assist shaft is applying some power assistin the clockwise direction as viewed in FIG. 16 a along the steeringshaft 1615 from right to left, the variator 1640 is in a ratio providinga slight output torque in that direction. When the power assist shaft1615 is applying some power assist in the counter-clockwise direction asviewed in FIG. 16 a along the steering shaft 1610 from right to left,the variator 1640 is in a ratio providing a slight output torque in thatdirection. Therefore, the entire range of the ratios available inseveral embodiments of FIG. 16 a will be around the zero output range ashigh ratios are not typically required in such applications. However, inother applications, higher ratios ranges may be necessary and themechanical attachments should be designed to optimize the ratio rangefor each application.

Still referring to FIG. 16 a, this system 1600 provides a way ofadjusting the output of the variator 1640 to respond directly andmechanically to the action of the driver in turning the steering wheel.This system 1600 is merely one example of a directly responsive shiftingmechanism and many other such control mechanisms can be used. The keycharacteristics of many embodiments of such a control circuit for asteering system is that as the steering wheel 1602 begins to turn, thevariator 1640 should begin to apply an output rotation in theappropriate direction until an equilibrium is reached between the torqueapplied to the steering wheel 1602, the power assist provided by thepower assist shaft 1615 and the feedback force provide by the wheels ofthe vehicle, or rudder if in a water borne vessel, through the rack andsteering pinion 1675.

The steering system 1600 illustrated in FIG. 16 a accomplishes itscontrol function mechanically, but this can easily be programmed into ahydraulic or electric control system, as described herein, to achievesimilar or different results as desired. FIG. 16 b illustrates anadditional embodiment utilizing an alternative shifting mechanism. Inthis embodiment, the axial position of the idler 1618 is controlled in amanner similar to that described above for FIG. 16 a, in that the idler1618 has a recess 1619 in one of its ends, the input end in this case,and the shifter 1632 now extends from within the recess 1619 in theidler 1688 towards the steering wheel 1602. The shifter 1632 has aflange 1633 in this embodiment that is retained within the recess 1619by thrust bearings 1617 and a retention ring 1621 similar to theanalogous or same components of the previously described embodiments.The shifter 1632 extends toward the steering wheel 1602 and extendsbeyond the planet carrier 1603 where it terminates having a lead screw1660 formed on this end.

Still referring to FIG. 16 b, the lead screw 1660 can be any set ofthreads formed on the outer surface of the shifter 1632, but someembodiments utilize acme threads. The lead screw 1660 is engaged by aset of internal threads 1661, which is a set of complimentary threadsfacing inward and engaging with the lead screw 1660 and which aremounted on the inside of a shift ring 1664. The shift ring 1664 is atubular ring having the internal threads 1661 formed upon its internalsurface and which is rotated about the steering shaft angularly by ashifting motor 1662. The shifting motor 1662 is mounted to a fixedsurface and is capable of rotating the shift ring 1664 about thesteering shaft in either direction in order to engage the internalthreads 1661 with the lead screw 1660 and thereby move the shifter 1632axially depending on the direction of rotation of the shift ring 1664.The shifting motor 1662 is an electric motor in the illustratedembodiment, but could also be hydraulic or pneumatic. In alternativeembodiments, the lead screw 1660 is replaced by a piston (not shown) andthe shift ring 1664 and internal threads 1661 are replaced with apneumatic or hydraulic cylinder (not shown), wherein the piston ispositioned within the cylinder by a hydraulic or pneumatic controlcircuit, which are common in the art.

Still referring to FIG. 16 b, the activation of the shifting motor 1660is determined by an indicator 1665 and a sensor 1666. The indicator 1665is mounted on the steering shaft 1610 and indicates any angular motionby the steering shaft 1610 to the detector 1666. The detector 1666 isarranged radially around the indicator 1665 and detects the magnitudeand direction of the angular rotation of the steering shaft 1610. Theindicator 1665 and detector 1666 can be any type of component capable offulfilling their described functions such as, but not limited to, rotaryencoders or any other such devices. The indicator 1665 and detector 1666can also comprise multiple components such as where the indicator 1665is an annulus extending from the steering shaft 1610 and the detector1666 is capable of reading the position or motion of the annulus. In oneembodiment, the indicator 1665 comprises an annular gear that moves arack, which creates linear displacement and the detector 1666 is alinear encoder capable of very fine motion detection.

Still referring to FIG. 16 b, the detector 1666 provides a motion signalto a controller 1667 via one or more signal lines 1668 and thecontroller 1667 sends motor control signals to the motor via one or morecontrol lines 1669. The controller 1666 can sample the position ormotion of the steering shaft 1610 by controlling the detector 1666, orthe detector 1666 can provide a set of position signals to thecontroller 1667 at a specific rate. The faster the motion signals aresampled, the more sensitive the response of the power assistance. Forexample, in one embodiment the controller can receive signals from thedetector at a rate of between 5 and 20 million signals per secondalthough higher or lower frequencies can be used as are common in theindustry. In other embodiments, the indicator 1665, the detector 1666,the controller 1667, the signal lines 1668 and the control lines 1669are replaced by the power steering pump and rotary valve system ofcurrent power steering systems in conjunction with the cylinder andpiston described above. Such a system is common in current steeringsystems and can be implemented as described herein.

FIG. 16 c illustrates yet another alternative embodiment for a powerassisted steering system 1600. Only the differences between theembodiments illustrated in FIGS. 16 b and c will be discussed. In theillustrated embodiment, the shifter 1632 is angularly aligned with thesteering shaft 1610 by splines 1663 or keyways and keys or other suchstructure and thereby rotates with the steering shaft 1610. In someembodiments, ball splines or other low friction structures are used asthe splines 1663 in order to ease the turning force required by theoperator. As with the previous embodiment, the lead screw 1660 and theinternal threads 1661 engage one another to create axial movement of theshifter 1632 in reaction to rotation of the steering wheel 1602.However, in this embodiment, the internal screws 1661 are fixed by aretaining ring 1662 to a support structure rather than to a rotatingmotor. Therefore, the internal threads 1661 do not rotate about thesteering shaft 1610.

In the illustrated embodiment, as the steering wheel 1602 is rotated byan operator, the splines 1663 rotate the shifter 1632, which rotates thelead screw 1660, which engages with the internal threads 1661 to developan axial force that changes the axial position of the shifter 1632 inorder to change the position of the idler 1618 and develop an outputtorque to respond to the steering of the operator. The gain or reactionrate of the steering system 1600 response of the illustrated embodimentto the input steering by the operator can be adjusted by controlling thepitch of the internal threads 1661 and the corresponding lead screw1660. The shifting mechanisms described for the various embodimentsillustrated in FIGS. 16 b-c can be used for any of the transmissionembodiments described or incorporated herein in order to achieveadvantageous shifting control and manipulation.

Gearing Systems

Due to the extremely configurable nature of the embodiments of the IVTsand CVTs described and incorporated herein, and the high degree withwhich the components can be easily scaled in size to accommodate theamount of torque and rotational power to be transmitted, the IVTs andCVTs make extraordinarily advantageous gear sets. Either reduction gearsor step-up gears can be configured by the various embodiments herein asthe input disc, output disc, and variator of each embodiment create acontinuously variable planetary gear set as described herein. Theaddition of an additional fixed ratio planetary gear set or additionalCVTs lined up in successive arrangement allows designers to achieveinfinite gearing ratios and flexibility. For instance, the variator 401of FIG. 7 can be combined with a planetary gear set as illustrated inFIGS. 11, 16 a-c to create the speed reduction system illustrated inFIG. 17. FIG. 17 is a schematic view of a transmission system 1700 thatcan suffice as such a continuously or infinitely variable gear set. Theillustrated transmission system 1700 includes a planetary gear set 1730,a variator 1740, and an output shaft 1710 that receive and transmitrotational energy from an input torque source 1720. The torque source1720 can be an engine, a motor, a piece of industrial equipment, adifferential, a shaft, or any other source of rotational energy.Additionally, although this schematic illustration shows the outputshaft 1710 connected to the output disc 1711 of the variator 1740, itshould be understood that the output disc 1711 can easily be connectedto the cage 1789 or the idler 1718 of the variator 1740 as well, asdescribed and illustrated herein and in copending U.S. patentapplication Publication No. 10/788,736 incorporated above (hereinafter“the '736 application), and this description applies to thoseembodiments as well. Furthermore, although the illustrated embodimentshows the ring gear 1737 as being fixed and the planet carrier 1733 andthe sun gear 1735 of the planetary gear set 1730 as being attached tothe input disc 1734 and the cage 1789 of the variator 1740,respectively, any of the connective combinations identified in thetables of the '736 application can be used and the following discussionapplies to those as well.

Such variable gear sets can be used effectively in any system thatutilizes or transmits rotational energy or converts linear motion intorotational motion or vice versa. In systems where a variable input speedis provided and a fixed or relatively constant output speed is desired,the embodiments of the CVTs or IVTs described herein are exceedinglyadvantageous and useful. For instance, superchargers and turbochargersfor combustion engines have efficiencies and performance characteristicsthat vary as a function of rotational speed either independently of oneanother or even dependent upon one another. However, the prime moversfor these components, direct connection to the crankshaft for thesupercharger and a turbine driven by exhaust gases for the turbocharger,also vary in supply speed or force depending on the rotation speed ofthe engine, which varies with throttle position. Therefore, in suchapplications, a variable speed gear set such as those described hereincan be used to reduce the adverse effects of the changing input speedwhen a desired output speed of the pump of these components is desired.

For instance, a supercharger is typically utilized on diesel-poweredvehicles such as semi-tractor trailers used in long-haul transportationof goods. The boost in intake pressure supplied from the supercharger tothe engine is affected by the rate of rotation of the crankshaft of theengine. It is desired to maintain the speed of rotation of thesupercharger near a target speed at various conditions. Existingsuperchargers use a fixed ratio speed changing gear set to change theengine speed to the rough speed range used by the supercharger. Throughthe use of a continuously variable gear set as described herein, thespeed of the supercharger could stay in a smaller range of operationalspeeds over the entire range of engine speeds thereby allowing increasedefficiency of the supercharger over the entire range of engine speeds.This is also true for any pump or turbine application. Most, if not all,centrifugal pumps and turbines have performance characteristics thatvary with the speed of their respective prime movers. In all suchapplications, the use of the continuously variable gear sets describedherein can be used to maintain the performance of these items in theirpreferred operational windows even as the speed of their respectiveprime movers varies within or out of the resultant desired speed range.

The planetary gear set 1730 can be any ordinary planetary gear set or itcan be any advancement in such structures. For example, U.S. patentapplication Publication No. 2003/0232692 (hereinafter “the '692application”), the entire disclosure of which is hereby incorporated byreference, discloses an example of an advance in planetary gear systemsthat can be implemented with the embodiments of IVTs disclosed herein.The variability created by the advancement disclosed in the '692application can be utilized to further increase the variability of theIVTs described herein, allowing such embodiments to fulfill even morefunctions. Similarly, U.S. patent application Publication No.2003/0153427, the entire disclosure of which is hereby incorporated forall that it discloses, discloses an advancement in planetary gearsystems in which the planetary gear set varies the input to output speedratios as a function of the load transmitted through the system. Again,such a system can be used in the IVTs described herein to create agreater range of effective ratios, or to vary the torque transferringcapabilities of the transmission system.

Control Mechanisms and Systems and Protocols

Many advances have been made for controlling the transmission ratio ofpast CVT designs such as toroidal and adjustable pulley CVTs. Many ofthese control systems can be adjusted and revised to take advantage ofthe advanced design and increased efficiency of the IVTs and CVTsdescribed herein. For instance, U.S. patent application Publication No.2003/0228953 A1 (hereinafter the '953 application) describes a controlsystem and shifting protocol for a CVT that is utilized on a variablepulley-type CVT that can be adjusted as described herein to takeadvantage of many of the embodiments described above to provide ashifting control protocol and system, and the entire disclosure of thatapplication is incorporated herein by reference. In the CVT described asbeing controlled in that published application, clutches and brakes arerequired that allow the transmission of that application to shift fromforward transmission ratios to reverse transmission ratios. Many of theembodiments described herein allow a transmission to shift from itshighest forward transmission ratio to its highest reverse transmissionratio through its continuous shifting range without changing theengagement of any of the components of the transmission.

The '736 application incorporated above describes numerous combinationsof input, throughput and output of the embodiments of the IVTs describedtherein. Many of those can be successfully utilized as the transmissionfor a vehicle such as a car. In one embodiment, such as that illustratedin FIG. 17, where the planetary gear set 1730 is positioned on the inputside of the variator 1740, the crank shaft 1720 from the engine of a caris provided as input to the planet carrier 1753 of the planetary gearset 1730 of the transmission 1700, the cage 1789 is free to rotate, thering gear 1737 is fixed to the case (not separately identified) of thetransmission 1700 or to some fixed support structure of the vehicle, theidler 1718 is free to rotate and the output shaft 1710 is connected tothe output disc 1711. In such an embodiment, the range of possibletransmission ratios is affected by the ratio of the circumference of thering gear 1737 to that of the planet gears 1736, or the PG ratio forthis configuration. Some embodiments utilize a PG ratio between 1.5 and10. In other embodiments, the PG ratio is between 2 and 5, while instill other embodiments a PG ratio of between 3 and 4 is utilized. Someembodiments use a PG ratio of 3.

Some embodiments of the IVTs described herein conforming to these PGratios provide transmission ratios adequate for many applications andprovide high efficiency, suitable transmission ratio range andoperational simplicity for nearly any vehicle using such a transmission.For instance, with a PG ratio of 3, some IVTs of the embodimentsdescribed herein that are configured as just described can provideengine input to transmission output ratios ranging from about 2.5forward to 0 forward all the way to 2.5 in reverse without everdisengaging any of their components. This setup also allows the coaxialalignment of the input shaft and the output shaft, thereby leading todecreased overall size, reduced and simplified resultant torsionalstresses and various other advantages known to those of skill in theart.

To incorporate the control functions of the embodiments described in theabove-mentioned '953 application with many of the IVTs described andincorporated herein, the clutches and brakes are removed and the ECUdescribed in that control system is operably connected to the servocontrols or the pneumatic or hydraulic controls utilized to control theIVTs so that the control system can be implemented and its advantagescan be exploited and amplified. The fully continuous, manually shiftedand staged protocols described in the '953 are all employed with many ofthe IVTs herein to provide performance that is significantly improvedover the embodiments described in the '953 application.

Another example of the use of embodiments of the IVTs described hereinas an advantageous improvement of existing technology can be illustratedwith reference to U.S. patent application Publication No. 2003/0109347A1 (hereinafter “the '347 application”), the disclosure of which isincorporated herein in its entirety. In the '347 application, ahydromechanical IVT is utilized on a tractor to maximize thefunctionality of the tractor where multiple speeds are desirable forvarious functions. Again, the IVT of that embodiment utilizes clutchesand brakes to vary its speed over its range of transmission ratios. TheIVT described in the '347 application, as with others like it, utilizesa parallel power path, that is two paths through which rotational poweris transmitted from the input to the output that are not collinear withone another. This configuration requires a synchronization of componentsof the transmission in order to shift the various stages and realize thefull transmission ratio range. This adds unnecessary parts andcomplexity, and therefore cost, to the transmission. In contrast, manyof the IVTs described and incorporated herein utilize a collinear pairof power paths that do not require synchronization or clutching andbraking in order to vary the transmission ratio over its entire range.Additionally, because power can be output via any one or many possiblecombinations of the output disc, the cage and the idler, the IVTsdescribed herein, provide for both power output to the drive train aswell as a power takeoff unit so that the same transmission can performboth functions simultaneously.

Referring also to U.S. patent application Publication No. 2001/0044358(hereinafter “the '358 application) the entire disclosure of which isincorporated herein, another system for controlling a CVT is describedthat responds to requests by vehicle operators for changes in vehicleperformance. In this embodiment, only belt-and-pulley and toroidal CVTsare contemplated, which require parallel power paths as well assynchronizing of components and the use of brakes and/or clutches toshift modes throughout the range of transmission ratios includingreverse transmission ratios. Many embodiments of IVTs and CVTs describedand incorporated herein can be advantageously implemented along with theCVT control system of the '358 application, as well as otherpublications incorporated above and below, by removing the controlsystem and functions that require manipulation or adjustment of theforward/backward switching mechanism. Specifically, the manipulation ofthese components adds an additional calculation in the response to ademand for a change in driving conditions made by the driver. Throughthe use of the certain embodiments of the IVTs described andincorporated herein, such as for example the embodiment illustrated inFIG. 17, the response is simpler for the electronic control unit toemploy and there is less chance of failure and a smoother resultingspeed variation over the entire range of driving conditions.

Furthermore, because many of the IVTs and CVTs described andincorporated herein are analogous if not similar to existing planetarygear set-based automatic transmissions, many of the existing advancesfor controlling existing automatic transmissions can be advantageouslyemployed on those IVTs, while employing the CVT and IVT controlprotocols described in the incorporated patents and publishedapplications. For example, U.S. patent application Publication No.2003/0027687, the entire disclosure of which is hereby incorporated byreference, discloses a control system that operates the engine inconjunction with a transmission controller. Any of the transmissioncontrol systems described herein can be used with such a control systemin order to maximize vehicle efficiency regardless of enginedisplacement. Other such improvements can advantageously be employed aswell.

As a further example, many of the embodiments of IVTs and CVTs disclosedand incorporated herein can also be advantageously employed inconjunction with the control systems disclosed in U.S. patentapplication Publication Nos. 2003/0162633 (hereinafter “the '633application”), 2003/0158646 (hereinafter “the '646 application”), and2001/0046924 (hereinafter “the '924 application”), the disclosures ofall of which are hereby incorporated in their entireties. While the '633application and the '646 application both operate a CVT that appears tolack reversing functions on its own, and the '924 application operates aCVT that includes the reversing mechanisms of other past advances, whichinclude a planetary gear set and clutches and brakes, all of theseapplications control a belt-and-pulley CVT that is hydraulically orpneumatically controlled. Therefore, each of these applications requirethe manipulation and control of brakes and clutches in order to achievethe complete transmission ratio range spanning from high forward to highreverse. This means that the power train throughout the transmissionundergoes connections and disconnections as the transmission ratio isvaried over the entire range of ratios, and this may lead to decreasedperformance, safety or component life. The present embodiments of theIVTs and CVTs that utilize these control systems achieve their functionsthroughout their transmission ratio ranges without the switching andbraking previously required.

U.S. Pat. No. 6,390,946 (hereinafter “the '946 patent”), the entiredisclosure of which is hereby incorporated by reference, discloses asystem designed to assist in the sensing of rotational speeds of variouscomponents. The '946 patent discloses the construction of a sensingsystem that can be applied to any of the rotating components of the IVTsand CVTs described and incorporated herein in order to provide speedsignals to the transmission control system. Additionally, U.S. patentapplication Publication Nos. 2002/0095992 and 2003/0216216, the entiredisclosures of both of which are hereby incorporated by reference, bothdescribe additional sensing points and systems of a rolling traction CVTthat can be utilized by the control units of embodiments described andincorporated herein to optimize the performance of the engine andtransmission of those embodiments.

The signals provided by such sensing systems can be utilized by thesystems described above or by, U.S. patent application Publication Nos.2002/0173895, 2003/0135316, 2003/0135315, 2003/0045395, 2003/0149520 and2003/0045394, the entire disclosures of all of which are herebyincorporated by reference. These are additional control systems that canbe implemented for use with the IVTs and CVTs described and incorporatedherein. As mentioned previously, only the belt-and-pulley and toroidalCVTs were contemplated for use with these control systems and thereforethe functional components and commands controlling the forward/reverseswitching brakes and clutches can be removed to allow control of thepresent embodiments. Furthermore, whether the method of shifting anyparticular embodiment is electric motor, pneumatic or hydraulic pistonor any other method, the systems incorporated herein can be adapted tosuch shifting mechanisms by any method known to those of skill in theart in order to achieve the advantages of the present IVTs and CVTs ascontrolled by the control systems described and incorporated above andbelow.

Furthermore, many advances have been made in the specific area ofhydraulic control systems for controlling toroidal and belt-and-pulleytype CVTs. Many of these systems and advances can be implemented for usein the hydraulically controlled embodiments of the IVTs and CVTsdescribed and incorporated herein. For example, U.S. Pat. Nos.5,052,236, 5,090,951, 5,099,710, 5,242,337, 5,308,298, 6,030,310,6,077,185, 6,626,793 and 6,409,625 as well as U.S. patent applicationPublication Nos. 2003/0158009, 2003/0114259, 2003/0228952, 2002/0155918,2002/0086759, 2002/0132698 and 2003/0158011, the entire disclosures ofall of which are hereby incorporated by reference, disclose hydrauliccontrol systems and control fluid systems as well as pressure system foruse in either a toroidal or a belt-and-pulley transmission system. Thesecontrol systems and circuits can be implemented on the IVTs and CVTsdescribed and incorporated herein by adapting these systems to operatethe piston of the hydraulically shifted transmission systems describedherein. Furthermore, U.S. Pat. No. 6,464,614 discloses a hydraulicsystem that provides hydraulic supply circuitry or passages in thecasing containing the remainder of the transmission system. Any or allof these systems or advances, or even combinations of them, arebeneficial in various applications of the IVT and CVT embodimentsdescribed and incorporated herein.

Such hydraulic control systems can include feedback control informationas well. U.S. patent application Publication Nos. 2003/0050149,2002/0169051, 2002/0155910, the entire disclosures of all of which arehereby incorporated by reference, each discloses a hydraulic controlsystem for an existing CVT or IVT. These publications also disclose themonitoring of certain system parameters to be fed directly back into thecontrol circuit, either mechanically or electronically, to adapt thecontrols to the response of the transmission system to the existingcontrol signal. Such feedback signals can provide very advantageouseffects when utilized along with the control systems described above foruse with the IVTs and CVTs described and incorporated herein, such aspreventing hunting for the proper output speed, reducing overall time toachieve the desired speed change, and increased overall vehicleefficiency.

However, these applications describe control units that are utilized ontoroidal or belt-and-pulley CVTs but that can be advantageously employedwith many of the IVTs and CVTs described herein. Again, by removing theswitching of clutches and brakes that must be accomplished in the pasttransmissions, all of the advantages disclosed in these publishedapplications can be enhanced. The hydraulic controls that operate thesheeves or pulleys of these transmissions can be simplified to operatethe hydraulic piston and cylinder control system used to control certainembodiments of the IVTs and CVTs as described above. Furthermore, thecircuitry, controls and the functional signals that manipulate theclutches and brakes of these three published applications can be removedand replaced with a control regime that simply adjusts the ratio of theIVT or CVT throughout its entire range. Many of the IVTs and CVTsdescribed herein also allow removal of the torque converter of the '924application and any clutches that may be utilized with that advance.However, these components can still be utilized in certain embodimentsas conditions may dictate.

For example, some embodiments utilize a clutch prior to the transmissionthat controls an amount of torque applied to the transmission,independent of the variability of the torque supplied by the engine. Inmany of such embodiments, control systems are utilized that adjust theclutch in order to prevent slippage of the rolling contact surface. U.S.patent application Publication No. 2003/0069682, the entire disclosureof which is hereby incorporated by reference, discloses a control systemand protocol that is used by such embodiments to control and preventslippage of the clutch and the transmission.

Control Protocols

In addition to these and other systems that can control a CVT or an IVT,there are many control protocols that can be utilized to maximize theadvantages of such a transmission in a vehicle. Because of the inherentdifferences, and indeed advantages, of a CVT or an IVT as compared to astandard geared transmission, operational paradigms can be abandoned inorder to achieve the increased efficiency and performance available fromthese advanced designs. Several advances have been made in the area ofcontrol protocols for CVTs or IVTs that can be implemented for use withmany of the embodiments of the IVTs and CVTs described and incorporatedherein. U.S. Pat. No. 5,820,513 (hereinafter “the '513 patent”), U.S.patent application Publication Nos. 2003/0229437 (hereinafter “the '437application”) and 2003/0022752 (hereinafter “the '752 application”)relating to establishing operational protocols for controlling a CVT asengine speed varies, and U.S. patent application Publication No.2002/0028722 (hereinafter “the '722 application”) relating to a controlsystem and protocol for an existing IVT, each disclose ways ofcontrolling CVTs or IVTs, and the entire disclosures of all thesepublications are hereby incorporated by reference. These publicationseach describe systems and methods for operating a variator of a CVT thatis used in a vehicle to optimize the performance of the vehicle;however, these publications only contemplate the use of existingtoroidal or belt-and-pulley transmissions and therefore would benefitgreatly from the implementation of many embodiments of the IVTs and CVTsdescribed and incorporated herein.

There are other examples of control protocols and performance mappingmethods that have been developed for existing CVTs and IVTs as well. ForExample U.S. patent application Publication Nos. 2003/0119630 relatingto mapping of CVT performance and function to develop shiftingstrategies, 2002/0165063 relating to controlling the emissions andtreating the intake of the engine in conjunction with transmissioncontrols for increased efficiency and/or performance, 2002/0062186relating to operating a CVT while traveling uphill or downhill,2002/0082758 relating to calculating a target speed ratio andcontrolling the CVT according to the target, the entire disclosures ofall of which are hereby incorporated by reference, each disclosecontrolling methods and techniques that are employed for use withcertain embodiments of the IVTs and CVTs described and incorporatedherein.

Other examples of such control protocols that can be employed along withsome of the IVT and CVT embodiments described herein are provided inU.S. patent application Publication Nos. 2002/0132697 relating tocontrolling a CVT having a multi-stage torque sensor, 2003/0022753relating to simultaneous controlling of a CVT and an engine in responseto a requirement for power output, 2003/0060681 relating to specificcontrol equations for operating a toroidal CVT, 2003/0119627 relating todetermining the transmission ratio of a CVT, 2003/0004030 relating tospecific methods for operating a CVT for increasing efficiency andperformance, 2002/0128115 and 2002/0115529 relating to establishing atarget speed ratio and generating a creep torque based upon thedifference between the target speed ratio and the actual speed ratio,and 2002/0072441 relating to compulsory down-shifting of thetransmission based upon various conditions, the entire disclosures ofall of which are hereby incorporated by reference. The embodimentsutilizing one or more of these advances achieve various functionalityand performance advantages that make these embodiments desirable forvarious applications. However, again, because these publications onlycontemplate either the toroidal or belt-and-pulley transmissions, theyinclude control componentry and functionality to control theforward/reverse mechanisms and can be optimized for use with theembodiments described herein by removal of such components andfunctionality.

Again, these publications describe inventions that are improved throughthe benefits of the simpler and more versatile design of many of thepresent embodiments including the variator 1740 and transmission system1700 described above and illustrated in FIG. 17. The collinear multiplepower paths of the IVTs described herein provide not only smallerdesigns, with simpler torsional reactive forces, but as noted before,also allow shifting of the transmission throughout its entire range ofratios without the need for mode shifting brakes and clutches. Incertain embodiments, this results in the input being connected to theoutput in the same manner over the entire range of transmission ratios,thereby leading to increased component life and performance as well assimpler bearing wear and other advantages. As a contrast, the IVT systemof the '722 application requires the actuation of a recirculation clutchor a direct clutch depending on the particular driving conditionsdemanded by the driver. Furthermore, the enclosing case of many of thepresent embodiments described herein can be made in a much simplermanner as fewer bearing and support surfaces need to be incorporatedinto the case. In some embodiments of the present IVTs and CVTs thatimplement the control systems and protocols disclosed in the '513patent, the '437 application, the '752 application and the '722application, the control mechanisms and functions that actuate theseclutches or brakes are removed from the control routines in order tosimplify the control system and protocols. By doing so, theseembodiments allow a simpler system and protocol for operating andcontrolling the IVTs or CVTs while still realizing all of the advantagesof such transmissions.

Alternative Architecture

Certain embodiments also take advantage of other mechanical advances intransmission systems. For example, as stated above, multiple planetarygear sets can be combined to form compound systems of gearing to operatein unison with the CVT of certain embodiments of the IVT in order to addadditional range or functionality to the resulting transmission system.U.S. patent application Publication No. 2002/0169048, the entiredisclosure of which is hereby incorporated by reference, disclosescompound planetary gear sets in order to facilitate the use of atoroidal CVT in an IVT, however, this publication also suggests howmultiple planetary gear sets may be aligned or combined in order tofunctionally combine them. Through reference to the illustrations andaccompanying descriptions of that publication, present IVT or gearingembodiments can be created that utilize such compound gearing.

Furthermore, U.S. patent application Publication No. 2003/0125153, theentire disclosure of which is hereby incorporated by reference,discloses a vehicle having power transmitted from the engine via a CVTto all four of its wheels. Embodiments of the IVTs or CVTs describedherein are easily incorporated advantageously for use on such a vehiclepower train for improved performance and to reduce maintenanceassociated with the transmission. Certain embodiments of IVTs and CVTsdescribed and incorporated herein incorporate advances disclosed in U.S.patent application Publication No. 2003/0186769 relating to twoplanetary gear sets coupled to each other and to two variators in acompound arrangement, and the entire disclosure of that publication ishereby incorporated by reference. This compounding and the various modesavailable are good examples of how such combinations can be effectivelyincorporated in certain embodiments of the IVTs and CVTs describedherein. U.S. patent application Publication No. 2003/0220167, the entiredisclosure of which is also incorporated herein by reference, disclosesa CVT that employs multiple sets of planet gears in its planetary gearset. Embodiments of the IVTs and CVTs described and incorporated hereinutilizing multiple sets of planetary gears for additional transmissionrange and additional advantages benefit from the disclosure of thispublication in carrying out such compounding.

Also, advances in planetary gears themselves are exploited by certainembodiments. For instance, certain embodiments utilize advances such asthat described in U.S. patent application Publication No. 2003/0171183,the entire disclosure of which is hereby incorporated by reference. Thispublication discloses a speed ratio amplifier for use with advanced CVTand CVT control systems to amplify the speed changing effect of aplanetary gear set. Embodiments of the IVTs and CVTs described andincorporated herein can achieve even greater ratio ranges for thetransmission as a whole.

Related Technology

Additional technological advances can be implemented for use in the IVTsand CVTs described and incorporated herein as well. For instance,because the embodiments described herein are rolling traction forms oftransmissions, lubrication is required for many embodiments and advancesin the field of lubrication can be advantageously implemented to promotethe proper and efficient operation of those embodiments. For example,the methods and systems of lubrication described in U.S. patentapplication Publication No. 2002/0183210 and U.S. Pat. No. 6,500,088 areemployed in many embodiments to advantageously lubricate thetransmissions of those embodiments, and the entire disclosure of both ofthose publications are hereby incorporated by reference. Additionally,the lube oils disclosed in U.S. patent application Publication No.2003/0013619 are used in many embodiments as traction and lubricatingoils, and the entire disclosure of that application is herebyincorporated by reference.

The lubricating systems of many embodiments, as well as the transmissioncomponents themselves can require additional heat dissipation. U.S. Pat.No. 5,230,258, which is hereby incorporated by reference in itsentirety, discloses a method of providing cooling to the transmission.Certain embodiments utilize a casing that utilizes the cooling channelsdescribed therein in order to provide the proper amount of cooling tothe lube oil and transmission components.

Furthermore, improvements that have been made for toroidal CVTs thatrelate to generation and control of axial traction force are employed insome embodiments. For example, the biasing mechanism described in U.S.Pat. No. 4,893,517, the entire disclosure of which is herebyincorporated by reference, is utilized in some embodiments of the CVTswhere it replaces the more complex axial force generators (“AFGs”)described herein and in some embodiments of the IVTs where it can easilybe positioned on the output side of the variator or between the planetcarrier and the input disc. The planet carrier of such embodiments candrive the cam flange of the AFG and the input disc is modifiedaccordingly to accept the thrust and the torque from the cam flange. Theimprovements to such AFGs that are described in U.S. Pat. Nos. 6,287,235and 6,514,171, the entire disclosures of both of which are herebyincorporated by reference, are utilized by some embodiments utilizingsuch AFGs.

Additionally, the double-sided preloading described in U.S. Pat. No.4,968,289 (hereinafter “the '289 patent”), the entire disclosure ofwhich is hereby incorporated by reference, is utilized in someembodiments where the preloading spring of that publication ispositioned on the output side of the IVT or CVT embodiment or ispositioned on the same side as the cam flange. For instance, in someembodiments the preloading springs are located between the planetcarrier and the case and apply force to the planet carrier that istransmitted to the input disc, while in other embodiments, the springsare located between the case and the second input disc in the dualcavity design, which applies a force against the input shaft asillustrated in the '289 patent. Many embodiments utilize the integraltorque sensor disclosed in U.S. patent application Publication No.2002/0111248, the entire disclosure of which is hereby incorporated byreference, as an input to control systems to adjust the axial force, forhydraulic and pneumatic AFG embodiments, or as an input for slipdetection functions or for any other function.

A hydraulic AFG is utilized in some embodiments to carefully control theaxial force applied according to the torque to be transmitted. U.S.patent application No. 2003/0100400 (hereinafter “the '400application”), the entire disclosure of which is hereby incorporated byreference, discloses a hydraulic AFG. Some embodiments implement thisdesign by creating a two part output disc having a piston part facingthe ball and a cylinder part that houses the piston part and therebycreates a chamber between the two parts that is sealed dynamically, asillustrated in the '400 application. As pressure is applied to thechamber, the two parts tend to separate and the piston part is pressedagainst the balls. Other embodiments implement this by attaching theplanet carrier to the cylinder part and forming the input disc as thepiston part. In such embodiments, the axial force can be carefullyplanned over the range of torques to be applied, and more importantly,can be adjusted or corrected without changing the components of the AFG.U.S. patent application No. 2003/0109340, the entire disclosure of whichis hereby incorporated by reference, discloses a dynamic seal that manyembodiments implementing hydraulic AFGs utilize to improve theirrespective performances.

As another example of the implementation of advances made for toroidalCVTs, certain embodiments herein utilize the taper bearings described inU.S. Pat. No. 5,984,827 to act as combination bearings. Severalcombination thrust-radial bearings are described for use in theembodiments of the CVTs and IVTs described and incorporated herein, andmany if not all such bearings can benefit through the implementation ofadvances in such bearing technology. Furthermore, some embodimentsutilize one or more of the improvements to these AFGs disclosed in U.S.Pat. No. 5,027,669 related to implementation of an axially moveableshaft, U.S. Pat. No. 5,899,827 related to a loading cam design, U.S.patent application Publication No. 2003/0017907 related to lubricationof ball splines, U.S. Pat. No. 5,984,826 relating to retaining thebiasing mechanism, U.S. patent application Publication No. 2002/0111244disclosing a hydraulic AFG, U.S. patent application Publication No.2003/0078133 related to a preloader accompanied by a hydraulic AFG andU.S. Pat. No. 5,027,668 related to creating a centrifugal lubricationreservoir at the AFG, all of which are hereby incorporated by referencein their respective entireties. U.S. Pat. No. 6,248,039, the entiredisclosure of which is hereby incorporated by reference, discloses animprovement to the use of ball splines for the mounting of a disc to ashaft where the disc and the shaft can move axially with respect to oneanother. Some embodiments utilize this improvement for at least one oftheir splines, regardless of the AFG in use.

U.S. Pat. No. 6,312,356, the entire disclosure of which is herebyincorporated by reference, discloses a way to accommodate a certainamount of flexing of the input or output disc. Some embodiments utilizesuch an improvement on at least one of the input or output discs toaccommodate a certain amount of elastic deformation of that tractiondisc, or those discs. U.S. Pat. No. 5,267,920 (hereinafter “the '920patent”) discloses the use of pilot holes to angularly align componentsduring manufacture, and its entire disclosure is incorporated herein byreference. Certain embodiments utilize pilot aligning holes as describedin the '920 patent in order to correctly align the components of any orall of the variator, the AFG or any other components.

Several advances have been made in the treatment and preparation ofmaterials for use in rolling traction CVTs and IVTs that are utilized bycertain embodiments as well. For instance, some of the bearings of someembodiments experience high load and/or high cycling and thereforebenefit from bearing advances made for other mechanical applications.Some of the bearings that can experience high load and/or high cyclingare the ball axle bearings, the idler support bearings, and othersimilar bearings. For instance, some embodiments described hereinutilize for one or more of their bearings, bearings made according toU.S. patent application Publication No. 2003/0219178, which isincorporated herein by reference in its entirety. Additionally, therolling elements of some or all bearings of some embodiments arecontained in bearing races formed according to U.S. patent applicationNo. 2002/0068659 the entire disclosure of which is hereby incorporatedby reference. Such bearing races can improve performance of the bearingover the life of the component.

In some embodiments, bearings that are expected to experience highlevels of stress are treated as disclosed in U.S. patent applicationPublication No. 2002/0082133, the entire disclosure of which is herebyincorporated by reference. In some embodiments, at least a part of oneor more of the input disc, output disc, balls, idler, or any of thehigh-stress bearings of the IVT or CVT is, or are, manufactured asdescribed in any or all of U.S. patent application Publication Nos.2002/0086767, 2003/0087723, 2003/0040401, 2002/0119858 and 2003/0013574,the entire disclosures of all of which are hereby incorporated byreference. In embodiments where the rolling contact surfaces of theinput and output discs are detachable, the rolling surfaces are treatedfor hardness as disclosed by these publications while the input discs ofsome such embodiments are manufactured for strength and durability asdisclosed. Furthermore, the bearing cages that retain many of thebearings of some embodiments are manufactured according to U.S. patentapplication Publication No. 2002/0151407, the entire disclosure of whichis hereby incorporated by reference.

In addition to these material composition and treatment advances, someembodiments utilize technology that is specific to the field of rollingtraction transmissions. For instance, the traction surface of either orboth of the input and output discs disclosed in U.S. Pat. No. 6,527,667,the entire disclosure of which is hereby incorporated by reference, varyin roughness. Some embodiments herein apply such variation to at leastone of the input disc, the output disc and the balls so that at certainratios the active surface will have a different surface roughness thanthat for at least one different ratio. Similarly, at least one of thetraction surfaces of some embodiments conforms to the disclosure of U.S.Pat. No. 6,524,212, which is hereby incorporated by reference in itsentirety, to control and improve the traction oil film thickness.

In another manufacturing advancement, U.S. patent applicationPublication No. 2003/0096672, which is hereby incorporated by referencein its entirety, discloses the use of a datum on the output disc bywhich the rest of the disc is manufactured. In some embodiments, thisconcept has been incorporated and a radially flat surface is provided onthe input and/or output disc that acts as an indexing origin for themanufacture and fitting of the rest of the disc(s). In some embodiments,this flat surface occurs near the inside bore.

U.S. Pat. No. 6,159,126, which is hereby incorporated by reference inits entirety, discloses a method of preventing a shock of a CVT where avehicle's engine may start while the transmission has drifted away fromthe lowest ratio. Some embodiments utilize a biasing mechanism in orderto mechanically return the transmission to a zero output or otherdesired orientation, according to the incorporated patent to preventsuch a shock from occurring. In some embodiments utilizing hydrauliccontrol systems, this is accomplished by a spring of appropriate biasingdirection and force for the particular application.

Additional Applications

Many embodiments of the IVTs and CVTs described herein areadvantageously implemented in various applications such as agricultural,aerospace, aircraft, watercraft, industrial machinery and auto racingamong others. Certain advances have been made that utilize existing CVTtechnology that would see increased performance that could not have beencontemplated by the original inventors when those existing CVTs werereplaced by the IVTs and CVTs of many embodiments, described herein. Forexample, U.S. Pat. No. 4,922,788 (hereinafter “the '788 patent”), theentire disclosure of which is hereby incorporated by reference,discloses the use of two IVTs for use on a twin track-driven vehicle,one IVT for each track. By changing the output rotation speed of eachIVT independently, the operator can steer the vehicle without need forturning wheels or other steering system. The IVTs operate independentlyof one another to provide either forward or reverse rotation to theirrespective tracks to drive the vehicle. The existing IVTs utilized inthe 788 patent suffer all of the same defects as described above, namelythe toroidal CVT is inherently unstable and the ratio control system isalso inherently unstable, and requires in any practical embodiment aparallel power path and clutches and brakes to perform its IVT function.Due to the inherently unstable design, the toroidal CVT requiressignificant structural strength for its support and to house its controlsystem.

Therefore, the embodiments described herein provide smaller and simplercomponents that reduce cost, size maintenance and increase reliability.The embodiments herein allow use of CVTs and IVTs not only on heavy twotrack vehicles, but also on the wheels of tractors and light tractorequipment. A vehicle can be provided with a relatively small andlightweight transmission at every wheel to have all-wheel steering wherethe steering is provided by the transmission ratio of each particulartransmission.

In another application, some embodiments of the CVTs and IVTs describedand incorporated herein are used in place of the existing CVTs disclosedfor use in U.S. patent application No. 2002/0165060 (hereinafter “the'060 application”), the disclosure of which is hereby incorporated byreference in its entirety. The torque distribution system described inthe '060 application is greatly enhanced by the comparatively smallerCVTs and IVTs described herein and because the resulting input andoutput axes of such embodiments are collinear. Such an orientation makesembodiments of the present application an ideal candidate for use in thetorque distribution system of the '060 application and indeed makes sucha system even more practically feasible.

Another advantageous application of embodiments described herein is ahybrid vehicle, which is a vehicle with two power sources, asillustrated in FIG. 18. FIG. 18 is a schematic diagram of an embodimentthat could be used for a hybrid vehicle without using a planetary gearset. For example, the combustion engine 1820 of a gas-electric hybridcan provide the input into the cage 1889 while the electric motor 1820provides torque input to the input disc 1834. The variator 1840 sums thetorque of the two inputs and provides a resulting output to the outputshaft 1810. In an alternative embodiment, inputs are switched so thatthe combustion engine 1820 of the gas-electric hybrid provides the inputinto the input disc 1834 while the electric motor 1820 provides torqueinput to the cage 1889. In other alternative embodiments, a planetarygear set is adapted to the input side in a similar manner as that ofFIG. 17 and torque is provided by the internal combustion engine 1820directly to the cage 1889 through a bore (not shown) in the sun gear andthe electric motor provides torque to the planet carrier, or vice versa.Such embodiments allow greater flexibility in designing a system thatoptimizes the efficiency of both torque sources, but add complicationand cost to the transmission 1800.

U.S. patent application Publication No. 2003/0032515 (hereinafter “the'515 application”) discloses a system for use in a gas-electric hybridvehicle, and its entire disclosure is hereby incorporated by reference.However, the '515 application requires two electrical machines tooperate, at any one time one acting as a motor and the other acting as agenerator. Embodiments of the IVTs and CVTs described herein areutilized in a vehicle as described in the '515 application, allowingremoval of the variable gear ratio by the engine and the second machine.Therefore, this leads to a much simpler design.

The embodiments described herein are examples provided to meet thedescriptive requirements of the law and to provide examples. Theembodiments described herein are examples provided in order to explainand to facilitate the full comprehension and enablement of all that isdisclosed herein and the description of these examples is not intendedto be limiting in any manner. Therefore, the invention is intended to bedefined by the claims that follow and not by any of the examples orterms used herein. Additionally, terms utilized herein have been used intheir broad respective senses unless otherwise stated. Therefore, termsshould not be read as being used in any restrictive sense or as beingredefined unless expressly stated as such.

1. A transmission comprising: a shaft; a plurality of power adjustersdistributed radially about the shaft, each power adjuster having atiltable axis about which it rotates; an input disc in contact with thepower adjusters; an output disc in contact with the power adjusters; anidler coaxial with and rotatable about the shaft, the idler in contactwith the power adjusters; a ball spline structure having ball splineunits that connect the shaft to one of the input or output discs, eachball spline structure having a ball gripped by a pair of spline grooves;wherein the ball spline units are arranged at equal angular intervalsalong a cross-sectional circumference of the shaft; and wherein thetotal number of ball spline units equals twice the number of poweradjusters.
 2. The transmission of claim 1, wherein the shaft comprises asplit shaft.
 3. The transmission of claim 1, wherein power adjusters arespherical.
 4. The transmission of claim 3, wherein the idler comprises aconcave surface in contact with the power adjusters.
 5. The transmissionof claim 1, wherein each power adjuster comprises a bore for receiving aspindle.
 6. The transmission of claim 5, further comprising one spindlefor each bore.
 7. The transmission of claim 6, wherein the spindles areadapted to be tiltable, and wherein a tilting of the spindles causes atilting of the power adjusters.
 8. The transmission of claim 1, furthercomprising a cage adapted to maintain a radial and axial orientation ofthe power adjusters about the idler, wherein the cage is further adaptedto rotate about the shaft.
 9. The transmission of claim 8, wherein thecage comprises: a disc-shaped input stator positioned between the poweradjusters and the input disc; a disc-shaped output stator positionedbetween the power adjusters and the output disc; and a plurality ofspacers adapted to rigidly connect the stators.
 10. The transmission ofclaim 8, wherein the input disc is fixed and does not rotate.
 11. Thetransmission of claim 8, further comprising a motor operationallycoupled to the cage.
 12. The transmission of claim 11, furthercomprising a planetary gear set comprising: a sun gear rotatable aboutthe longitudinal axis and coupled to the cage; a plurality of planetgears engaged with and adapted to orbit the sun gear, wherein eachplanet gear rotates about a planet shaft of its own; a ring gearengaging each planet gear; and a planet carrier rotatable about andcoaxial with the shaft, wherein the planet carrier retains and positionseach of the planet shafts.
 13. The transmission of claim 12, wherein themotor is connected to the planet carrier.
 14. The transmission of claim13, wherein each planet shaft extends from the planet carrier andterminates at a connection point with the input disc so that the planetcarrier rotates the planets about the sun gear and rotates the inputdisc about the shaft.
 15. The transmission of claim 12, furthercomprising an axial force generator adapted to generate a contact forcebetween the input disc, the output disc, the balls and the idler. 16.The transmission of claim 15, wherein the axial force generatorcomprises: a thrust washer coaxial with the idler, the washer having afirst side facing the input disc and having a set of thrust ramps formedon the first side; a set of thrust-receiving ramps formed on the inputdisc facing the thrust washer; and a plurality of thrust elements incontact with the thrust ramps and the thrust-receiving ramps.
 17. Thetransmission of claim 15, wherein the axial force generator furthercomprises: a bearing disc coaxial with and rotatable about the shafthaving a threaded bore; a plurality of bearing disc perimeter rampsattached to a first side of the bearing disc near an outer diameter ofthe bearing disc; a plurality of bearings adapted to engage theplurality of bearing disc perimeter ramps; a plurality of input discperimeter ramps mounted on the input disc on a side opposite of theballs, the input disc perimeter ramps adapted to engage the bearings.18. The assembly of claim 17, the axial force generator furthercomprising: a screw coaxial with and rotatable about the shaft adaptedto engage the threaded bore; a plurality of central screw ramps attachedto an end of the screw; and a plurality of central input disc rampsaffixed to the input disc and adapted to engage the plurality of centralscrew ramps.
 19. A method of manufacturing a transmission, the methodcomprising: providing a shaft; arranging a plurality of power adjustersradially about the shaft, each power adjuster having a tiltable axisabout which it rotates; providing an input disc adapted to contact thepower adjusters; providing an output disc adapted to contact the poweradjusters; mounting an idler coaxially the shaft, the idler adapted tocontact the power adjusters; providing a ball spline structure havingball spline units that connect the shaft to one of the input or outputdiscs, each ball spline structure having a ball gripped by a pair ofspline grooves; arranging the ball spline units at equal angularintervals along a cross-sectional circumference of the shaft; andproviding a total number of ball spline units equal to twice the numberof power adjusters.
 20. The method of claim 19, wherein providing ashaft comprises providing a split shaft.